Is gaming a sport? Depends on your definition of "sport". If all it requires is to be competing against someone else, then heck, even sandwich-making can be a sport if you're trying to do it faster than someone else.
Everyone will have their own definition of what a sport is. Mine excludes gaming, even though I do plenty of it. Then again, being a soccer player and having the view that sports require real physical effort, I don't even consider golf a sport (it's a game, but not a sport). Same with things like billiards (a favorite game of mine, but it isn't a sport). That's my view, and I'm sure everyone else will have their own.