I am not. Any more than you are. There is a lot of data, and for every claim find arguing it is Just the smoking ban, there are so many attributing the decline in pubs to other factors. The link previously shared by stonerblue being just one of them. I don't even want to go down the childish a-ha, look at this paragraph route, I trust people are mature enough to weigh things up themselves.
What there is also plenty of data for, is that it is has been o e of the most successful pieces of legislation in improvements to health and reduction in smoke related conditions. That far outweighs some already struggling pubs struggling more, while others embraced the change.