You cannot be bribed into or out of believing a god exists, you can only decide to fake it and take the money. That said an atheist faking to believe in a god, never will but there's a strong chance, if theists stops telling themselves god is real they may, over time, become atheists.
Of course your question has a comical side effect:
Theists are going to tell you that no amount of money could bribe them not to believe in god and yet they will argue communist USSR, China and Korea became atheist overnight. A bit of a double standard that and also lends a lie to their claim.