Among a burgeoning slate of programs concerned with superheroes, Madison Avenue expects CBS’ “Supergirl” and Fox’s “Gotham” to duke it out Monday nights this fall for the audience most coveted by advertisers: young people who don’t skip past the commercials. According to a Variety survey of primetime commercial-ratings projections by three big media-buying shops, “Supergirl” is expected to eke out a lead of a mere tenth of a point over the Fox drama in so-called “C3” viewership among audiences between 18 and 49 years of age.
