Darnda
You said originally "It's not the money or the principle I just want him around for as long as possible for me and our baby". The in the next post suggested an ultimatum.
You could go the ultimatum route. If anything will make him stop and decide what is more important than smoking, an ultimatum that he loses his marriage and child will do that.
You asked if ultimatums work. They only work if you are fully willing to embrace the answer you don't want. If he calls your bluff. If he thinks to himself "she wont really leave me over this". Then he's not going to take it seriously and is likely to dismiss the ultimatum as bullying and/or nagging.
However, if you really are willing to divorce over this, then an ultimatum may be the way to go. If you would genuinely rather parent solo, separate financially, live on your own with your child, manage co-parenting when separated and will cope with him finding a new partner and life - then I'd say your best chance to force him into the decision to give up would be an ultimatum.
I don't say that flippantly or lightly. Its a really big deal. Your sentence in the OP about wanting him around for you and your baby in later life says a lot about your feelings for him.
Unless you do something really massive like give a divorce or give up smoking ultimatum - and mean it - he's unlikely to give up until he makes that decision himself.
If you don't want to make that ultimatum and follow it through, your only option is to keep on being disappointed in him, outcasting and guilt tripping him and make your peace with the fact that he'll only give up when he is ready to give up.
m