I dunno. Seems pretty clear to me what he meant (emphasis mine):
He wouldn't start out by saying Giga won't necessarily be in Texas and then immediately contradict himself in the same sentence by saying it will be in Texas (as would be the case if "there" is referring to Texas). The only other misinterpretation of "there" referring to Texas would be if the new Giga won't necessarily be in Texas, but the Cybertruck definitely will be built at some other facility in Texas (rather than at the proposed Gigafactory, wherever it may end up).