In the Season 6 episode Epic Fail, Taub quits because when he learned that House wasn't coming back, he started searching for a new job. He got an offer to join a friends surgical practice.

Does Taub kill himself?

The show's producers confirmed that his death was indeed a suicide. In "Both Sides Now", Kutner appears briefly in one of House's hallucinations, along with Amber Volakis (who had previously died in Wilsons Heart).

Is Taub really the father of both babies?

Taub is the father of two baby girls born almost simultaneously to his ex-wife and ex-girlfriend.