1) First of all, don't let him snowball you. He's a poker player. He's currently using his poker skills on YOU the GM. If he bluffs you well, he wins easier, see.
2) See if Celebrity Poker Showdown is on DVD (I don't think they're running reruns right now or my Tivo would be full). Watch a few episodes. It's really good poker for beginers. If you can't find that, you can find a poker show to get some of the lingo.
3) Narrow it down to a single die roll (at least per hand), or two rolls with mathmatics giving a bonus or penalty to gambling. The roll represents luck of the draw. The character's skill represents his talent. I don't care if he's a grand master, if his character doesn't know how to play poker he's going to throw around tells like a rookie.
4) To reward the player for his own poker coolness, roleplay out key hands, like when his opponent tries to get him to go all in. Just pivotal stuff. Give him a bonus for how cool his bluffs and strategy is (like +15-+15). So while you have your single roll, it takes a series of them, with poker playing coolness, to play out a game (say in fifteen minutes.)
5) Have other people cheat. Have half-dressed women run into the room chased by murderous boyfriends, have the dealer drop dead of a heart attack or the pizza boy get tipped a thousand dollar chip. Things are always straight playing. Don't overdo it, though.
