As the PP said, if it is closing for a special event or hard ticket party, you will not be able to go into the restaurants.
On any other day, some restaurants may remain open for a while, but I would not count on it. If it is CS I would make sure I was in the restaurant before closing. Some of the TS restaurants have reservation times available for up to 15 - 30 minutes after closing, but I don't know if they would take any walk ups at that time.
At the MK the Main Street Bakery stays open a little later, but that's because the stores on Main Street also stay open an hour after the park closes.