If theHunter: Call of the Wild™ generated the same gross revenue on the Epic Games Store, Expansive Worlds would keep approximately $51,651,055 - that's $7,804,641 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $6,906,962. 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 $40,990,612.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.