If Wartales generated the same gross revenue on the Epic Games Store, Shiro Games would keep approximately $17,930,496 - that's $3,251,096 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $2,308,704. 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 $14,167,440.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.