Did Yusuf (Joseph), peace be upon him, rule according to what Allah revealed?

Your response is correct. No Muslim should doubt or hesitate that the prophets, peace be upon them, ruled by Allah's law. They are infallible from disbelief, ignorance, concealing the message, and error. Allah has favored and honored them with prophethood and messengership. Prophets are infallible from disbelief before prophethood, and after it from major sins and everything that compromises dignity, as well as from minor sins. What Yusuf (Joseph), peace be upon him, did by taking on a position under a corrupt man was permissible, provided that his work was done by his own hand without interference from the corrupt man. He was kind to the people, invited them to Islam, and established justice among them. Yusuf also affirmed that judgment belongs to Allah alone, and he, being infallible, could not rule by other than what Allah has revealed.