Today's Cincinnati Enquirer carries this story about how El Paso's ban on smoking hasn't hurt local eateries. And here's a recent story from The Miami Herald about a brouhaha in Athens, Georgia about similar legislation.
The latter piece cites some data that suggests restaurants (or more specifically, bars that don't serve food) do in fact suffer lost revenue from smoking bans.
However, the larger point from this ongoing debate has to be that once you get into a cost-benefit analysis of smoking bans, the fight is essentially over. That's because those analyses are embedded in a public health model which proceeds from the assumption that risky behavior needs to be minimized. It may take a couple of years, but once the issue is being decided on something other than the right of a business owner or an individual to do what they want with their own property/person, it's only a matter of time before the scope of permissible behavior is severely restricted.