South Florida said: "I'm not very knowledgeable about these things but it had the worst drop in attendance and isn't that a bad sign?"
Shows typically only close if the running cost (nut) becomes higher than the gross -- and usually if a show is early in the run, they're willing to put a few weeks in to where the gross is lower than the nut so the show can build an audience. Cher Show is still pretty new, and raking in over a million dollars a week, so it's definitely fine. Attendance doesn't really matter as much, other than the fact that it means fewer chances of selling full-price tickets.
Not to mention, the typical Thanksgiving boost tends to do well for family oriented shows, due to out-of-towners coming into the city for a "family" holiday (see: Frozen), and the extra day off from school that kids get. A big chunk of the audience for The Cher Show (gays) already live in New York, and they were busy visiting their families in the midwest.