It depends on what kind of knives you are interested in and not all gun shows are the same, so it is hard for anyone to say unless they have experience with the particular gun show promoter and locale. That being said, the larger gun shows in my neck of the woods (Central Texas) usually have at least 2-3 large knife dealers, another half dozen or so small dealers and/or makers as well as some knives scattered amongst the guns, ammo, tactical gear, jewelry, coins, military collectibles, jerky, etc. The knives range anywhere from absolute junk to quality collectables with much greater representation on the junk end of the spectrum. Some of the production knives I can recall seeing at a recent show are Benchmade, Ka-Bar, Cold Steel, Spyderco, Almar, Emerson, Mcusta, Chris Reeve, Moore Maker, Kershaw, Case, Boker, Ontario, ESEE, Puma, Buck, CRKT, and Gerber. There was one dealer with a nice selection fixed blade customs, mostly works of Dozier & Crotts.
My personal observations are that most the dealers know very little about the knives that they are trying to hawk at close to MSRP and that somehow makes me feel better about using them to handle a knife that I will end up buying elsewhere for considerably less if I like how it feels. I enjoy talking to some of the makers and knowledgeable dealers and have picked up some of their knives at bargain to fair prices, but most the time I leave without buying a knife.
Knife shopping at gun shows is a mixed bag and may not be for you but fondling knives to the sweet aroma of beef jerky and cinnamon-vanilla roasted pecans on a Saturday morning sure sounds better than mowing the yard. Of course the yard still needs mowing and you just blew maybe $15 on gas, parking and entry fee just to fondle a few overpriced knives so keep that in mind.