Israel is occupying the West Bank, absolutely. The IDF is literally everywhere, conducts military operations all the time, and huge chunks of the land are under direct Israeli administration.
None of those things is the case for the Gaza Strip. That border was established in 1949 following negotiations between Israel and Egypt, and afterwards it was functionally a part of Egypt. It was then captured and truly occupied by Israel after the 1967 Six Days War. This lasted until 2005, when the IDF fully withdrew from the Gaza Stop (the boundary of which, I'll say again, was established in 1949) and forcibly evicted all Jewish settlers. A military blockade was instituted after Hamas won elections in 2006 and started lobbing rockets at Israel, since Hamas' explicit goal is the violent elimination of all Jews from the entire region.
You can say that the blockade is unjust, collective punishment, destroys any hope for prosperity, and anything else. I'd even agree with you on a lot of that. But you cannot say that it is an occupation, because that is a word that describes a specific situation that simply is not happening in Gaza.