Actually deposits are irrelevant here. You can deposit $20 and spend hours wagering and generate a nice comission. Or you can deposit $1000 and make one bet and generate next to nothing.
Actually deposits ARE relevant!
Actually you are both correct. The amount of the deposit matters only to the extent of the play-through it can generate which can be calculated with a statistical certainty.
I have an article titled Bonus Terms Explained and sections 7-10 calculates play-through using the stats from Phoenician Casino and slot game Bush Telegraph.