I don't think Kirby intended a Zola/Skull relationship. Go check out Jack Kirby's 1978-1980 run of Cap books. Zola was some reclusive mad bio-scientist mucking around in a secret base with the head of Ad*lf H*tler.
Mark Gruenwald introduced that Zola/Skull relationship to explain the resurrection of the Red Skull after the Skull's death in the mid 80s, Skull was dumped into a cloned body of Captain America, liken to H*tler's mind dumped into a cloned body to become the Hate Mongler in the FF and later in the Marvel Villain team up books.
The Skull was his "benefactor.". They did seem to have a relationship.