I've heard Gabe Kaplan plays poker now...

Question

but all I've ever seen him do is be a commentator. Are there matches he's been in that I've missed?

Answer 1

Most poker commentators are also professional poker players (or at least were at some point).  That's how they got the job.

Answer 2

He was a poker player before the commentary gig.  He did sit in for daniel negranau for one episode of high stakes poker and did fairly decent.

Answer 3

Gabe Kaplan became a professional poker player after he left "Welcome Back Kotter".  I've never seen him play a match, but it must have been lucrative for him.