If DYNASTY WARRIORS 8: Xtreme Legends Complete Edition generated the same gross revenue on the Epic Games Store, KOEI TECMO GAMES CO., LTD. would keep approximately $10,512,690 - that's $2,155,284 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $1,297,185. 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 $8,266,913.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.