The first two pubs in our town to introduce smoking bans (well ahead of the legislation) saw no decrease in their clientele, although I couldn't say for sure if the number of customers actually went up.
But despite my mistyping above, this chap from UKIP is not talking about pub closures is he? Whether or not they were caused by smoking bans. He's talking about people going home with a bottle of wine and a six pack instead of going to the pub, which admittedly if it were done on a large enough scale would lead to closures and maybe in the odd case actually has done. But either way, comparison with the effects of communities of pit closures, or large factories etc, is ludicrous. Even if you go as far as saying that such things might have their upside, Because surely there is an upside to people not smoking in public in confined spaces (!)