Do the Invasion weapons have killstreak kits?
Having a quick look at the Community Market, it turns out you can use Specialised Killstreak kits on them. As of right now, there are two different Invasion weapons so far that have kits applied to them, those being the Giger Counter and Batsaber, proving that the weapons can have kits applied to them. The item descriptions even show that they have a visible sheen and active killstreaks.
It seems like the kits used on them may well be blank kits, which is proven by the fact that the Wrangler (the weapon that the Giger Counter is a reskin of) doesn't have any kits at all.
We don't really know for sure yet, but recent discussions suggest not. Blank killstreak kits can be used on the items.
TF2 was updated on October 15th to include killstreak kits for all invasion weapons. These killstreak kits are separate from their non-reskinned counterparts, meaning there are separate Machina and Shooting Star killstreak kits.
Invasion killstreak weapons obtained before October 15th were due to a temporary bug a while ago where generic killstreak kits could be obtained, which allowed almost any item in the game (including hats) to have killstreaks applied to them.