If Layers of Fear (2016) generated the same gross revenue on the Epic Games Store, Bloober Team SA would keep approximately $7,764,967 - that's $1,683,743 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $922,495. 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 $6,081,224.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.