If STAR WARS™ Battlefront™ II generated the same gross revenue on the Epic Games Store, DICE would keep approximately $41,534,630 - that's $6,738,070 more than on Steam.
At this revenue level, Epic's concrete platform fee would be $5,527,450. 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 $32,943,456.
Note: This is a hypothetical comparison. Actual sales volumes differ significantly between platforms, and Steam's larger user base typically drives substantially higher sales.