Let's play with some numbers. If 400,000 people die a year from tobacco smoke, and the median salary in the united states is roughly $50k in 2007 according to Wiki. And say that they only pay 20% income tax and we forgo the additional taxes on purchases, property, etc. then that is 400,000 x 50,000 (remember this is median so half will fall below and half will be higher) and that is 2x10^10 which is $20,000,000,000 in taxes. This once again does not include additional taxes. Even if you cut that in half because this is the household income where two are combining to make 50k, it's still a big chunk of change.
Now to me I would think keeping them alive is more money than banning electronic cigs and having them die off with analogs.
I don't know if my number playing is correct as there is a lot of variables .... but I still would think it's in the favor of the government to keep people alive to work.
Maybe someone else can negate my statement, confirm, or add to it.