If A Plague Tale: Requiem generated the same gross revenue on the Epic Games Store, Asobo Studio would keep approximately $21,652,916 - that's $3,800,999 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $2,816,307. 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 $17,128,456.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.