I think it'd be possible to get photos of Times Square virtually empty, though a frame without either a pedestrian or a taxi would be difficult. Was looking through my old photos and found two near such shots, at around midnight...however, I almost always try to capture at least one person in a frame as a reference point for the scene, so I didn't try very hard to get an empty scene :)
Mostly because I was waiting for people to come into the frame? And because it was around midnightish, a time when people are still leaving Broadway theaters (yes, even during snow) It's "virtually" empty compared to what Times Square is like on a stereotypical day (or night). I think if I waited till around 2-3am, or 5-6 am on a weekday
http://www.flickr.com/photos/zokuga/5297956792/
http://www.flickr.com/photos/zokuga/5296132766/
OK, they were during snowstorms, but still :)