Yes! I loved it. I think Wally was playing tiles. Here are my reasons:
Wally looks like the kind of non-Asian player one would find at a tile table.
Dilbert is the scientific type, who normally are sticklers for using correct terminology. Calling pai gow poker "pai gow" is incorrect and lazy. I know most people do so anyway, but I have higher expectations for Dilbert.
In the second frame, Dilbert says that pai gow is "a difficult game to learn after a few adult beverages." Note that he said "learn," not "play." Pai gow poker is not that hard to learn. If you understand how to play poker, then pai gow poker can be easily explained in under a minute. Meanwhile, tiles is difficult to learn as well as play.
The cartoon came out on Chinese New Year. This may have been an inside joke.
In the unlikely event Scott Adams should read this, I would welcome a definitive answer.
This question was discussed on my forum at Wizard of Vegas.