If Dead by Daylight generated the same gross revenue on the Epic Games Store, Behaviour Interactive Inc. would keep approximately $208,143,630 - that's $22,031,239 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $28,246,859. 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 $165,473,342.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.