If ULTIMATE MARVEL VS. CAPCOM 3 generated the same gross revenue on the Epic Games Store, CAPCOM CO., LTD. would keep approximately $4,060,864 - that's $926,086 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $417,391. 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 $3,134,779.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.