Wait a second.
It is hard to understand, if you mean playing CS:GO profesionally, on tournaments for money, or you just mean betting on the result of the match.
I assume that you mean the second thing, because in other case you wouldn't post here, I guess.

So, I have been basically doing some kind of that gambling, it is all about which team is going to win.
Most of the sites use CS:GO skins as a currency, every one of them has some value, so you bet the skins, and you get the payout in different skins.
There are also some websites that just use regular money, but to be honest, I dont know any casino from that kind.