Was it called the Benny Vandergast Theater or the Benny Vandergast Memorial Theater? Oddly enough, Kermit said in the episode where the theaters name is mentioned that the muppets owe a lot to Benny, including three months rent, which would imply that Benny was still alive and still the owner of the theater, but Scooter's uncle is named J.P. Grosse, not Benny Vandergast (and ironically, this was mentioned in the episode where Scooter got hired because his uncle owned the theater).
It's been awhile since I read the page for Muppet Theater at Muppet Wiki, but I believe that page said that it was first referred to as the Muppet Theater in It's a Very Merry Muppet Christmas Movie. Is this true? I could have sworn that I knew it was called The Muppet Theater long before that movie. I certainly thought it was called the Muppet Theater back in 1994 or 1995, a few years before I even got the internet. Was it ever called the Muppet Theater on The Muppet Show, or possibly in a storybook?