Winnings will vary with each game, and it also depends on what you’re comparing them to. In terms of max pay out, they are similar to regular video slots; but again, it will depend on which exact games are being compared. As any pro will tell you, video slots can easily have max payouts from 2,000x to well over 20,000x your bet size.
Megaways do tend to be in the high volatility range though. What this means is that payouts tend to be less frequent, but when they happen they tend to be bigger.