If Dinkum generated the same gross revenue on the Epic Games Store, James Bendon would keep approximately $10,576,539 - that's $2,164,716 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $1,305,892. 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 $8,317,701.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.