Then Quark devotes his entire holosuite to just Vic Fontaine's program?
It was Quark's decision to keep Vic's program running continuously IIRC.
Consider Professor James Moriarty and Countess Regina Bartholomew who after Ship in a Bottle spent the rest of their lifes living (unknowingly) inside of a computer module, they didn't need a holodeck to live their lives.
And it was the same way with Vic, he continuiously experiences his life in 1962 Las Vegas because his program is running 26 hours a day. However it wasn't neceassary for the holosuite to be playing that program all that time. None of the holosuites is dedicated to the program, the suite (all of them) can be used from other holoprograms, even while Vic's program is ongoing.
Vic's program only occupies a holosuite when someone want to enter it.