All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ‘alayhi wa sallam, is His slave and Messenger.
You should have gotten rid of that pack of cigarettes. As long as you gave it to your aunt without knowing that she would give it back to your uncle, then we hope that you bear no sin for that.
It is feared, though, that your aunt shall bear a sin for having given him the pack while knowing that he would smoke it and while she also believes that smoking is haraam (prohibited). She must repent and give your uncle advice gently and wisely, perhaps he would respond to her.
Allah knows best.