I have not had a huge whale myself (less than $10k depositor), but in the past one of my old affiliates from the past program I use to run got 2 players who all lost in excess of $500,000 each meaning he made over $250,000 in commissions from them alone. They were both sportsbook players.
This is rare, but also shows that it can be done… and is one reason why I decided to take affiliate marketing seriously.