What is the ruling on accepting a receiver as a gift from someone whose money is unlawful, and must one donate the receiver itself or its value in charity?

If all the wealth of your relative is illicit (haram), then it is not permissible to deal with him in it. If the device given to you does not have a specific owner, you can spend its value for the benefit of Muslims or donate it to the poor and needy, and it becomes permissible for you to benefit from it. Your relative should be advised to repent and dispose of the illicit wealth by spending it for the benefit of Muslims or giving it to the poor and needy. He should not benefit from it himself or for his family, unless he is poor, in which case he may take from it what suffices his needs. Whatever portion of it is in his possession and belongs to a specific owner, he is obliged to return it to them; otherwise, he should donate it on their behalf.