Is it permissible for employees and their heirs to benefit from a life insurance policy paid for by the the employer, assuming the employer receives the amount from the insurance company and hands it over to the heirs, and is this money considered a gift, analogous to the Prophet’s (peace be upon him) acceptance of a gift from charity money after the giver had taken possession of it?

There is no harm for the heirs of an employee in accepting the amount that the employer contributed to the insurance. However, anything exceeding that is not permissible because it is money acquired through a corrupt contract. They must dispose of it by spending it on the welfare of Muslims or giving it to the poor and needy, if they know that it is the very money taken from the insurance company. But if this money has mixed with the employer's money, then there is no harm in taking it.