At least four, maybe five? Can't be sure, might be only three.
Very similar to this one in daylight, and it had only three:
But the truck in front is also a load so there's two semis as was pointed out by @scottf200 in his post below, and in a video clip posted on 𝕏 by S.E. Robinson, Jr. That's at least six in the daylight footage and not sure if the night shot is one of those same carriers or not. Either way, a lot of Cybertrucks being transported for testing!