What is the ruling on the salary of a husband who works as a fine arts teacher and teaches drawing animate beings? Is there any suspicion or unlawfulness in it, especially since he teaches a fine arts aptitude course that covers details of drawing people and faces?

It is not permissible to teach fine art that involves drawing animate beings (those with souls), nor is the money earned from it lawful, because it is in exchange for a forbidden benefit. However, there is no harm in the wife and children taking from the husband's salary earned from this work, because his money is mixed and not entirely unlawful. Dealing with someone whose wealth is mixed is permissible. If all his earnings are unlawful, it is permissible for you to partake of it out of necessity if there is no other money that suffices you. The wife should continue to advise her husband with wisdom and good counsel to transition to a permissible occupation.