If anything, Snape is a deliberate inversion of Heathcliff. So I suppose in that sense, JKR might have had Heathcliff in the back of her mind.

Heathcliff deliberately sets out to completely ruin the lives of everyone who ever crossed him. He destroys the children of his enemies, including his own son and Cathy's daughter. As an adult, Heathcliff has few to any redeeming qualities. Even his obsessive love for Cathy is hardly redeeming, since he uses it as an excuse to torture those around him. (He tortured Isabella, which he told her he would do.)

There is no real redemption for Heathcliff, except perhaps (and I find that arguable, given the rather sadistic and utterly unreliable nature of the novel's narrator, whose final lines should be viewed with great suspicion) in his death. Snape, meanwhile, spends his adult life protecting the child of the man he hated. He teaches Harry, even despite his loathing. He attempts to ensure that Harry has a future. Hell, he even steps between the Trio and a freaking werewolf. He tried to save even Sirius Black.

And any comparison between Lily and Catherine is so asinine that I can't even grasp it.