Is it permissible to work in a store that sells cigarettes and other permissible items, despite the need and debts, and after the store owner refused to stop selling cigarettes?

It is impermissible to sell cigarettes if it is highly probable that the buyer will use them for unlawful purposes. If you can limit your work to selling permissible goods, then there is no harm in it. Otherwise, it is not permissible for you to work in it, except out of dire necessity that makes the forbidden permissible. This necessity is to be estimated by its measure, and whatever exceeds what is needed to satisfy it should be spent on the welfare of the Muslims.