My guess is at 4-5k dead at least, with 3-4 times that in wounded.Remember not all casualties are dead soldiers, wounded soldiers would be much higher. Furthermore Israel also suffered casualties at the north in their clashes with Hezbollah.
I will take a guess and say.. The IDF suffered a total of around 3 thousand dead from the clashes in Gaza plus near Lebanon with Hezbollah. And around 11 thousand wounded from clashes at the two fronts of Gaza & Lebanon.
Dead and wounded for Hamas should be about equal or even less.