According to my dictionary research, both will work… In one definition, American Heritage specifies that “youth” is preferable when discussing a collective, i.e. there may be two “youths” standing in front of the drugstore, but the “youth” of the nation loiter daily…

However, in the secondary definition there is no specification, except to confirm that the “no s” version is used with both s. and pl. verbs.

I see a higher incidence of youth with no s on google…