The show will require any dealer selling firearms at the show to have an FFL, no exceptions. You can still rent a table without an FFL, but you can't sell firearms.
*Some* shows will require you to have an FFL to get a booth- it depends on the policies of the show operator (and state law, as well, probably). Plus, there are many things besides guns sold at gunshows- it would be silly of them to require me to have an FFL in order to sell flag cases and other items that I make (which I do). I occasionally sell a gun or some ammo at a show- nothing has ever been said about it.
You do not need a FFL to rent tablespace to sell non-firearm items, but in many states you will absolutely need one to sell firearms. Apparently there are exceptions, which IMO unwisely plays into the narrative of the Party of Evil.