The idea of this fight is not to earn on bets, but to earn on selling PPV subscriptions and commercial. Betting in this fight is just like an addition.
How is it possible to expect earnings from bets? These fighters if they are expecting earnings from bets they need to participate in rigging the fight for them to benefit, and that is illegal therefore it's not happening here. Their income will be derived only from PPV revenue and probably gate entrance too if the crowd is already allowed.