How long a walk is the Watkins glen gorge?

This depends on how much you stop for photos and crowds....30-75 min

Depends on witch trail you take

There's a few different paths/loops you can do. You could see the gorge in 15 mins or walk the entire thing in 2-3 hours

I don't remember, but I would start at the top. It's been around 50 years since I was there, last.