No, not surely. This is basic economics. The price isn't influenced by what it costs to produce. The price is set according to what users are willing to pay. What users are willing to pay is influenced by how much money they think it's worth, how much money they have and how costly other options are.
In case of Fortnite there is no competition (no one else can offer that game and there isn't really any similar option) so additional money comes purely from developer's pocket. Sure, they could have been charging more to make a point or because they think iOS users are willing to pay more in general but the users don't really care where 30% of the price goes to. It doesn't influence their buying decisions at all.
I mean that’s literally what Epic was doing.