First, neither the Israelis, nor the Palestinians, not anyone else will be able to really know what effect this ground operation will really have on the ground. It will take a least 48 hours to get a sense of what really happened on the ground in military terms.
Second, the outcome will be result of *perceptions*. If Hamas fights Israel from day one until the exit of the Israelis then this operation will be deemed as a failure by most people. If Hamas "folds" and accepts some kind of "deal" then it will be an Israeli "victory".
Thirdly, time is on Hamas' side: following the first 48 hours, each passing day things will see things get worse for the Israelis. Therefore, my guess is that if Hamas succeeds in actively resisting for one week or so the Israelis will essentially be defeated. If Hamas "folds" it will be very soon, in the next couple of days.
For the first time in their history the Palestinians have the opportunity to inflict a painful defeat upon the Israelis. Hopefully, they will seize it.