I don’t think the argument as a whole is a fallacy, it’s true that the exact cost to the NHS is more than covered by tax, but most estimates of wider cost to the economy (e.g. lost productivity, disability benefits, etc) is higher. https://fullfact.org/health/farage-smoking-revenue-nhs/

It's equally a fallacious argument to try to fit "cost to the economy", whatever that means, to the healthcare cost (usually this is done to inflate costs to fit the narrative). By that logic, ban everything and allow only what allows individuals to maximise their productive labour... what a nightmare.