Yes Russia is likely if allowed, to be able to send grain to export and a lot would probably go to the EPs as its easier to obtain than US grain and also can be countered against Russia's own imports.
The thing with grain shortages in 1917 was I think less with actual shortages and more with horrendous mismanagement and problems with the railways meaning a lot of the crop was rotting in sidings. If this could be avoided or significantly reduced then even with exports occurring you could see the revolution possibly avoided or at least no earlier than OTL.
I had thought the grain shortages were a function of the breakdown in the rail system per Norman Stone's book, but this article indicates it was a multi-factoral problem that was simply inherent in mobilizing so many men and horses and taking them away from food production, since Russian agriculture was based on the small family farm:
Prior to World War I, many authorities believed that countries with substantial agrarian sectors and grain exports, including the Russian Empire, could overcome war hardships more easily than those countries that imported grain. This column asks why the experts got it wrong in the case of...
cepr.org
On 29 October 1917 (16 October in the old Russian calendar), Sergei Prokopovich, the Russian minister of food procurement, had to acknowledge in public that there was little or no grain in government storage to feed the army and residents of the capital. On the Eastern front, St Petersburg and the Russian army in the south had grain reserves for a week, but armies in the north had grain for little more than one day and some of their regiments were beginning to starve. Prokopovich worried that open clashes over grain distribution between producers and consumers could destroy the Russian army and state (Prokopovich 1918). As it turned out, his fears were realised. Ten days later, the Bolsheviks overthrew the Provisional Government and seized power in Russia, holding it for more than 70 years.
Russian difficulties with grain procurement were not well anticipated. Before the war, many authorities believed in fact that those countries with substantial agrarian sectors and grain exports, including the Russian Empire, would switch to food autarky and overcome war hardships more easily than those countries that imported grain (Broadberry and Harrison 2005). Why did the experts get Russia wrong? Why, instead of victory, did Russia’s Great War end in defeat and revolution? The economics and politics of the Russian grain and labour markets provide the answer. In short, it was impossible simultaneously to mobilise 15 million males into the Russian army, procure the grain to feed them as soldiers, and avoid revolution.
It's a longer article, but has substantial data in it so would encourage anyone interested to read the whole thing, as it gets into more than just the problem of manpower mobilization. Peasant hoarding was also a major issue and one insurmountable without using Soviet levels of force...which explains Stalin's behavior later on.
The important point though is that exporting grain would be a disaster for Russian food supplies given the mobilization of so many farmers and horses and peasant refusal to sell especially at government prices. I mention horses more than the article does, but the same dynamic played out in Germany and A-H once the labor and manure of horses were lost to farmers.
This article indicates social breakdown, with peasants and local authorities pillaging train shipments before they got to the cities:
Also if we're assuming a fully neutral Turkey that doesn't block the straits then Russia can import a lot of the military stuff it needs a lot earlier which could have a significant impact on its military performance. In the early years while France and Britain are building up their capacity to supply their own forces most of this would have to come from probably the US and Japan but still a lot better than what they achieved OTL.
It is debatable how much it could actually import given the voracious demand of the French and British for equipment, as IOTL Russia had the lowest priority for US exports, but without Italy Russia could theoretically get everything Italy got IOTL from the Entente/US. I don't really know how much and what that was in terms of military equipment and how much was just raw materials, which Russia already mostly has everything it needed there.
The Japanese and US didn't really have a lot to send, Japan more because of its history conflicts with Russia and desire to reign supreme in the Fare East, the US because it was maxed out supplying the French and British. By 1916-17 there would be more slack to send to Russia especially without Italy in the war, but again with a neutral Italy A-H would be able to interdict supplies through the Straits with its navy, and without Italy in the war A-H would focus on beating Russia instead of having to divert large amounts of equipment and men to Italy. Containing Entente forces in Serbia supplied via Salonika wouldn't be all that hard given the limited rail capacity and domestic Serbian manufacturing, so it wouldn't reach Italian levels of resource commitment to serve as a historical analogue for that campaign ITTL.
Much will depend on the situation in 1915. Serbia will stay in the war due to Entente commitments in the Balkans being possible here without Gallipoli (5 divisions initially, 15 total assuming Salonika could handle that), which will of course attract some of the forces the A-Hs sent to Italy IOTL, but mostly be those the CPs (A-H and Germany) used to defeat Serbia IOTL in 1915. They'd probably balance each other out and Serbia remains a going concern for most of the war if not all of it, but a resource drain for the British and French.
But that means A-H has excess forces starting at some point in summer to use against Russia. Not all of what they had used against Italy would be needed to balance out the Entente in Serbia especially as the war goes on and 1915 is too early for the Entente to have enough extra stuff to send to Russia, especially as they will need quite a bit to keep Serbia in the war. Question is whether the extra A-H forces available will be enough to do sufficient damage to Russia in Ukraine to change the war situation compared to OTL 1915, especially if there isn't a major transfer to the Serbian front in autumn (IOTL those forces were taken off the Eastern Front, but ITTL the Italian front forces in May-June would be used in the Balkans) in addition to no continual build up of forces against Italy. Especially if A-H can maintain sufficient forces on their own to counter the Serbs and Entente Army of the Orient (OTL name for Allied forces in Salonika).
For the Austrian perspective on OTL operations in Autumn 1915 here is the english translation of volume 3 of the A-H official history:
(p.189 is an overview of autumn operations in East Galicia that could well be changed ITTL with extra Austro-German forces not needed to finish off Serbia or go to the Italian Front). If they achieve their goals ITTL of liberating East Galicia and splitting Russian forces the Russian Southwest Front would be pretty decisively beaten and a strong defensive line would be anchored on prime terrain and reserves then freed up to use elsewhere. Brusilov's offensive then wouldn't be able to achieve anything in 1916 even with greater Entente materials support given that there would be better defensive lines and no diversion of resources to Italy as well as a chance to preempt by the A-Hs thanks to having only 2 active fronts and plans to invade Ukraine in 1916. That would mean Verdun might have a shot of working ITTL since there wouldn't need to be major German diversions from the West if A-H could hold its own in the Balkans and Ukraine and perhaps even the proposed spoiling attack against the build up of British forces on the Somme could be launched with German reserves freed up:
By the spring of 1916 the staff of Germany's 2nd Army, deployed north and south of the River Somme, had concluded that a major Allie...
roadstothegreatwar-ww1.blogspot.com
Also I should note that the CPs won't be trying to finish off the Serbs in the Autumn of 1915 ITTL because Entente forces would prevent that from happening and more importantly there is no need to establish a rail link to the Bulgarians and Ottomans, since they are both staying neutral here. Instead the CPs can simply contain them with the forces they already had in place in 1915 plus some reinforcements not needed to counter the Italians. Logistics would be the big enemy of the Entente forces in Serbia given that they would have to rely on Salonika with its limited capacity and the rail links being limited into Serbia from Greece; that means they have enough to keep Serbia in the war, but not enough to break out and threaten A-H.
warfarehistorynetwork.com