If Five Nights at Freddy's: Help Wanted 2 generated the same gross revenue on the Epic Games Store, Steel Wool Studios would keep approximately $4,765,697 - that's $1,070,256 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $513,504. 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 $3,695,441.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.