Will the thesis tutor take senior students to write graduation thesis to earn extra money?
I don't know the details. Under normal circumstances, it is one of his duties to guide students to write their graduation thesis, without extra money, depending on the agreement and arrangement between schools or students. Some schools may give corresponding rewards according to their academic performance, but this is not the policy of all schools. I suggest you consult the relevant departments of the school or yourself to get more accurate information.