If GTFO generated the same gross revenue on the Epic Games Store, 10 Chambers would keep approximately $51,472,977 - that's $7,788,452 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $6,882,679. 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 $40,848,959.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.