ah, the old is it a sport question. I myself played chess for years while I myself considered it a sport there are a lot of people that don't and that even includes some people that play the come on decent level.
I am not going to repaid any of the arguments given if it is a sport or not just my view to when something is a sport or not.
A sport is in my view a competive game where you try to become the best there is. So in my opinion a sport is depended how you play it.
For example with chess if I play with my roommate Bob we just play for fun and I consider this a game because there is no competive level here. But if I play it in a chessclub I want to be the best I can be and rank up as high as I can and then I consider it a sport. In that way I also don't consider that kids that are playing soccer in there freetime sport because of the missing of the competitive element.
Saying that I have to say poker is mostly not a sport because the main goal for most players is only to gain money. granted the only way to earn more money is to become more skilled in the game still it isn't the primairy goal.
Still for some pro's being the best is there main goal and I think at that level you could consider poker an sport.