Just throwing some numbers around...
I figure maybe 5 million smokers in Australia.
Guesstimated average amount smoked per smoker: 1 pack every 2 days.
Equates to roughly 2.5 million packets per day.
$10 tax per pack, that's $25 million per day.
Over a year that's $9.125 billion.
I dunno what the figures are for daily expenditure within the health care system are for smoking realted illnesses tipsy2, but I'd guess that $25 million per day would just about cover it, and leave you enough change to pick up some duty-free smokes on your way out.
As Chimbu Chuckles states, that's why they will not ban smoking, but they are not shy of making life bloody difficult for smokers while they try to make it look like they care.
Cigarette taxes paved the way for the kind of thinking where they can just stack huge taxes onto things like alco pops, and claim it all to be for altruistic reasons. "No, it's not for the money at all, we're just looking out for you, because you're obviously too dumb to look after yourself".