So, Sam said it was luck...and it's true there has never been any indication that Sam's demony powers can control cards...
BUT, it is established fact that using powers makes you sweaty...see Max Miller and Sam's initial visions. (Max was always covered in a small sheen of sweat. Sam would start sweating just before a vision hit.)
I just looked at some caps from the episode and Sam was DEFINITELY sweaty during the final moments of the game. Yes, you could argue that it's nerves and panic...but it's an interesting thought anyway. Dean may have been right when he told Sam in S1 that they should go to Vegas.