The short answer is yes, cue sports is an Olympic sport. It just isn't included in the games.
It seems this debate always comes around to who thinks it's a sport versus a game. But the reason this debate has some legs is because cue sports is recognized as a sport by the IOC, and that makes it at least possible to be considered for inclusion in the Olympics. So as far as this Olympic debate goes the point is moot. It is a recognized sport as far as the IOC is concerned. It just isn't an "official" sport, meaning it is included in the games.
Of course, whether it should be included in the games is a different debate. But keep in mind the IOC's criteria can be quite different than our own. They are not just concerned with whether the competitors sweat, get their heart rates up, requires years of extensive physical training, etc., but also in things like is the game widely played, will many countries be competitive, will it generate interest (i.e. make money), and does it reflect the "Olympic ideal"?
In regard to the Olympics what it has going for it in addition to having an international federation is that it is now played throughout many parts of the world so numerous countries would be competitive. Also, it apparently has drawn pretty good crowds at the World Games.
What goes against it are the perception of it's competitors as athletes (age and conditioning). Comparisons to some other events like curling are not really applicable since curling is in the winter Olympics, which has fewer sports and more room to add events. I'm not sure if the IOC has deemed cue sports as a summer games only type event, but it is the summer games that the WCBS has petitioned for inclusion in. The summer games is tapped out right now and anything new can only get in if another sport is dropped.