You are correct that exact figures are not available. You are right, taxes don't work that way. They are not directly earmarked for use on collection, rather they go into general revenue.

However efforts have been made to study the population wide effects of smoking. Smoking remains the #1 cause of preventable major illness.

From a public health perspective, it is cut and dried. Non smokers can work longer and be more productive, pay more tax and do more volunteer work. Raising taxes and preventing cheap imports forces smokers to pay closer to the actual costs of their addiction. In accounting terms they are required to internalize the costs of their decisions, rather than externalizing the costs to society as a whole.

Here is an article from 2019.

https://www1.racgp.org.au/newsgp/professional/smoking-costs-australia-close-to-137-billion