For example, Cruz could bolster his national standing through a prime time speech to the convention. Having a large bloc of loyal delegates puts Cruz in the position to demand such a concession from the Trump camp. Otherwise, Cruz will be lucky to be able to finagle a five minute appearance in the second hour of Fox and Friends.
Unless Cruz agrees to support the nominee, which he currently refuses to do, then he should get zero time. If he does, maybe 5 non-prime minutes. Besides does he have anything meaningful to say at the moment beyond apologizing for his lies?