I have to admit that given the choice between Trump and Cruz, it's almost a tossup. And not because of the quality of the candidates. They just both suck really bad. The only thing that makes me weigh towards Cruz is that I believe he would nominate the most pro-2a SCOTUS justice. I don't really care about anything else. All his other baggage is at least equaled by Trump's baggage. They just both suck that much.
So, if I were polled and somehow I thought Trump might actually nominate a 2A supporter instead of his sister, I might say I support Trump over Cruz. But there is a lot to the definition of "support" that is unsaid by those polls.
So, to paraphrase
The polls say Trump can't win
The polls say Trump can't win
The polls say ... what's that? Really?
The polls are inaccurate