You should look for a Pa. attorney who specifically handles tobacco litigation. If the loved one was a resident of a different state, check with attorney in that state.
Generally the statute of limitations for a wrongful death is 2 years in PA, however this may be shorter depending on the facts of your case. You should also be aware that big tobacco made major settlements in the late 90s for it's deceptive practices. At this point, nearly 20 years later when the harms of smoking are well known, I think you may have difficulty finding a lawyer willing to pursue a case. Best of luck to you though.