If Wolfenstein II: The New Colossus generated the same gross revenue on the Epic Games Store, MachineGames would keep approximately $37,309,703 - that's $6,113,933 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $4,951,323. Epic charges 0% on the first $1 million in annual per-app revenue and then 12% on the remaining amount. On GOG (30% cut), the developer would earn approximately $29,582,718.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.