No one who isn't an athlete, should be considered an "athlete". I'm sorry, but that's a stupid question. No, a pro gamer, is not an athlete. In fact many of them are considerably in bad shape and health, because they're not very active and have horrible diets. Pro racers are not athletes. Pro billiards or card players, are not athletes, and those are not "sports". Hell, pro golfers barely qualify as athletes, and honestly it's a tough argument to label them as such.
An athlete is someone who takes part in athletics, physical sports and activities. Not someone in who sits in a chair and presses buttons.