My betta fish is floating on its side at the top of the tank and looks like its dead but it isnt and its stomach is bloated. does it have dropsy?

100% yes.

I'm afraid it is highly unlikely that you will be able to save the fish at this point either.

Dropsy is usually a secondary symptom of another infection (usually bacterial). The dropsy is usually caused because the fishes immune system was unable to fight the primary infection, and it has caused organ damage, usually to their kidneys.

Dropsy can also occur for no apparent reason in an older fish. As with humans sometimes as fish age their organs begin to fail, as such they contract dropsy.

I offer my deepest hopes that your fish makes it.