It reduces use, but the people stubbornly still using tobacco are likelier to be poorer. No peer-reviewed studies are required to demonstrate that it's a regressive tax, any amount of "Think of the children!" posturing notwithstanding.
I'm fine with that. Cost was a factor in helping me quit. Considering the lifetime cost of being a smoker (both in past expenditure and probable future medical expenses) I wish cigarettes had been much less affordable when my parents were puffing away during my childhood. I loathed cigarettes and yet I was in a hurry to try them and sure enough became seriously addicted to tobacco.
Where think of the children == reducing incidence of lifetime addiction and horrible disease. Though I guess you have to pick your priorities.