Cards in Roll20

I have an RPG system that uses poker decks instead of dice and each player save GM has a 13 card deck and 3 cards in hand to 'cheat fate' so can you do this in roll20?

There is a card system in Roll20, and in fact a normal deck of playing cards is pre-loaded into every campaign. If your system has particularly complex or uncommon mechanics with the cards, it may not do what you want, though.

Well each player has a 13 card deck and the GM has a 52 card deck fights and skill tests require players to draw from GM's deck. And the players can alter results with their own play hands.

Sounds like you would need to make multiple decks (one per player and one for the DM) but it certainly sounds possible. There would likely need to be some social ruling to prevent players from using each others decks since it is either 'player accessible' or not unlike journals that can be assigned on a player by player basis. Check out the  wiki for the full details on how to use decks to achieve your dream :)