Ready for a lesson in citizenship law? You won't learn anything, but perhaps other readers will.
Cruz was born in Canada. Under Canadian citizenship law, that made him eligible for Canadian citizenship.
But, because his mom was an American citizen (there is no evidence to the contrary, just unsupported speculation), he was an American citizen-at-birth.
Accordingly, upon reaching his majority, he was eligible to claim what amounted to a dormant Canadian citizenship. He did not. Consequently, he remained an American citizen.
Again, American citizenship laws are unaffected by Canadian citizenship laws.
You dodged the question. The Dallas Morning News reported in August 2014 that Cruz was, at that time, a Canadian citizen. The DMN was correct. How did they KNOW they’d be correct, without access to Cruz’ immigration files?