If REMNANT II® generated the same gross revenue on the Epic Games Store, Gunfire Games would keep approximately $59,412,450 - that's $8,510,223 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $7,965,334. 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 $47,164,449.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.