It’s not clear to me whether this is true or not. At first glance it seems no it can’t be done, it’s seems like a classic irregular warfare situation (as seen in Vietnam, Afghanistan, etc.) Sure a large army fighting an irregular force can can kill a lot of fighters including decent number of senior leaders (plus of course a lot of civilians) but that does bot mean they defeat the irregular force and destroy its will or ability to keep fighting (particularly anywhere the large army doesn’t currently have troops)
The difference here is the Gaza Strip is not Afghanistan or Vietnam. It’s a tiny 10x50km pocket of land, surrounded on three sides by Israel (or Israeli controlled sea) and the Israeli army is large. They would be quite capable (at a significant cost on both sides, but most of all the civilian population of Gaza) of making sure there isn’t anywhere in the Gaza Strip that does not have Israeli troops. In those circumstances I’m not sure wiping out Hamas would be impossible (not that it would make anyone more secure)