Is the forty dinars that I took from a person who was semi-intoxicated and who said it was a gift, considered a debt upon me?

If the donor was not fully conscious due to intoxication at the time of the donation, then his donation is invalid. In this case, this money is considered a loan, and its equivalent must be returned to the lender or his heirs. If he cannot be reached, then the money should be given as charity on his behalf, and if he is found later, the lender is given the choice between taking his money or being content with the charity. However, if he can be reached, then one must go to him and inquire whether the money was a gift or a loan, and act based on his statement, because his actions while intoxicated are not considered valid.