Will Muslim employees who steal money from a store that sells alcohol and cigarettes in America be held accountable, thinking that they will not be held accountable because the store sells forbidden things?

My advice to you and your workers is to fear Allah Almighty, and to remember the perishability of this world and the Day of Judgment. You must repent from selling unlawful things and stealing the money of Muslims before death. It is not permissible for a worker to steal from his employer, even if the employer sells unlawful things, and it is not permissible for the worker to sell unlawful things in the first place.