If Automation - The Car Company Tycoon Game generated the same gross revenue on the Epic Games Store, Camshaft Software Ltd would keep approximately $7,180,799 - that's $1,564,254 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $842,836. 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 $5,616,545.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.