I wouldn't go that far. You can gather intel in a various amount of ways. From traditional spies and turncoats to access to advance drones or satellite equipment that can monitor movement. Hell, even hacking into cell phones and smart phones. If you can tag a known terrorist and you also tag the areas he tends to visit the most, you have an idea. Not to mention any sort of technological solution that the Israelis might have come up with to locate the tunnels.
It may not be enough though, depending on the goal. Israel seems more willing than before to simply occupy Palestinian regions, but that would mean urban warfare, which would be costly and might burn up what little political capital the Israeli PM has left. And it seems he is intent on gaining political capital from this, not losing it.
That isn't great for the situation though. Word has it that Hamas impart launched this attack to boost their ratings for their own coming elections. Losing this fight would be a political disaster within the Palestinian regions and they'd lose out to their rivals. Therefore, they're going to want to keep launching rockets until it gets to the point that they can either declare some kind of victory (even if it's a pyric one) or until doing so only furthers to weaken Hamas.