If all 4 screws are out, tap on the float bowl lightly with something like the plastic handle of a screwdriver.
Don't wail on it. Just keep tapping. You'll eventually see some daylight between the mating surfaces and with luck you may save the gasket if you resist the temptation to pull at the float bowl once it begins to loosen.
It'll come off. May take a few minutes, particularly if some dink used silicone or gasket sealer on it in the past.