They mention "billions" as if it's a huge number - the CBO charts are all denoted in billions. It's the smallest number worth mentioning from the perspective of the federal government. The federal government decides the budget of NASA. Ted Cruz is saying that none of the money, not even the new billions they're getting from tariffs, or the old 34 billion from customs duties or the 84 billion from excise taxes, or even the income tax, is worth diverting to go to Mars, so we should rely on private industry.
I get he's proclaiming the benefits of a public-private partnership, but it still feels suspiciously like he's declaring it can't happen because he says it won't.