Is a son who works as an accountant in his father's tobacco factory, and is religious, sinful, knowing that his father spends on him from the money of this factory?

It is not permissible to work in selling tobacco because it is forbidden (haram), and because whoever assists in a sin is like the one who commits it. Allah Almighty says: (And cooperate in righteousness and piety, but do not cooperate in sin and aggression). You must advise your father to abandon trading in it, and if he insists, you must immediately stop working with him, because there is no obedience to a creature in disobedience to the Creator.