If King Arthur: Knight's Tale generated the same gross revenue on the Epic Games Store, NeocoreGames would keep approximately $7,058,928 - that's $1,539,326 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $826,217. 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 $5,519,602.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.