What is the ruling on profiting from marketing a gaming website (g2a.com) through a referral links system that relies on multiple levels of commission, and are these profits permissible or forbidden?

For the promotion of games to be permissible, the game itself must be something that is permissible to promote. If the game is permissible, then any direct commission for the promotion is lawful. As for a commission given as part of an unknown wage, it is not permissible because it renders the contract one of Gharar (excessive uncertainty). However, if the commission is in the form of a promise or a conditional gift, then there is no harm in it; as it is permissible to make a gift conditional according to some scholars.