If ARK: Survival Ascended generated the same gross revenue on the Epic Games Store, Studio Wildcard, Grove Street Games, Instinct Games would keep approximately $82,136,905 - that's $10,576,082 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $11,064,123. 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 $65,240,720.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.