Cruz will deliver the beat down with a smile, highlighting policy differences. That’s what votes ultimately care about. Trump is playing with fire by attacking Cruz.
I believe that Cruz will understand how to deal with/react to Trump in the debate, without trying to blowhard against him, but also without mealy-mouthing. The main thing he’ll need to do is reach that happy medium between stating facts and figures and not coming across as a policy wonk which shuts off most people’s brains during these debates. He’ll need to appear serious but not remotely sour or buffoonish (I don’t think Cruz even has “buffoon” in him, despite the best efforts of the lapdog lackey media, which tries to make that buffoon Obama -though a dangerous one, through his hatred of America-look like a rocket scientist).