If The Legend of Heroes: Trails of Cold Steel generated the same gross revenue on the Epic Games Store, Nihon Falcom would keep approximately $4,852,855 - that's $1,088,084 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $525,389. 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 $3,764,771.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.