If Call of Duty: Advanced Warfare - Gold Edition generated the same gross revenue on the Epic Games Store, Sledgehammer Games, Raven Software would keep approximately $31,535,965 - that's $5,260,995 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $4,163,995. 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 $24,989,973.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.