Cruz might have been able to win, although he would not have been able to talk over the MSM’s head like Trump has done throughout the campaign. In light of this I would have to judge Cruz’s ability to win as being very improbable.
How would Cruz would have won Michigan, Wisconsin, Pennsylvania, Ohio with his lousy message of gays, abortions, and the constitution (that he seems to only care about on the campaign trail anyways)? Those issues would not have gotten the blue collar working man to vote for him, because when you lost your good job and working 3 sucky ones with Obamacare as your insurance, the last thing you care about is gay marriage or abortion.
Trump won because of his winning message resonated with this group. He did exact opposite of what traditional establishment republicans have been doing and losing the past 8 years.
Trump was winning this thing early on, why do you think the media was doing everything possible to stop him? They wanted Cruz to win or Kasich or JEB or any of the others but even they couldn’t prop those losers up during the primary.