If Middle-earth: Shadow of War generated the same gross revenue on the Epic Games Store, Monolith Productions would keep approximately $110,959,824 - that's $13,196,348 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $14,994,521. 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 $88,168,042.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.