The 1990 edition of “Black” says this of Natural-born citizen:” Persons who are born within the jurisdiction of a national government, i.e. in its territorial limits, or citizens temporally residing abroad.” Given that his natural mother is and always has been an American, Cruz qualifies.
The Supreme Court trumps Black. It was unanimous in exclusively defining natural-born citizens as “all children born in the country of parents who were its citizens.” It has also affirmed in multiple cases that the citizenship of a child naturally follows the status of the father, not the mother. Cruz does not qualify.