If this the interview you are discussing, it was not a question of amnesty. It was about birthright citizenship.
http://www.mediaite.com/tv/cruz-dismisses-megyn-kellys-immigration-question-as-liberal-media-tactic/
No, the question I heard was when Trump had just announced that all illegals would be deported. Kelly asked him point blank three times — would you deport ALL illegals like Trump. Cruz refused to answer, said that was a question that the press would ask, etc.
His position on birth right citizenship is about as murky.