If Brigador: Up-Armored Edition generated the same gross revenue on the Epic Games Store, Stellar Jockeys, Gausswerks would keep approximately $3,247,725 - that's $759,762 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $306,508. 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 $2,487,963.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.