Sasuke tells Naruto to infuse his Six Paths' power with his chakra to create a technique to block Madara's movements. Shukaku then tells Naruto to use his chakra in conjunction with it to create the sealing technique.[
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] The result is a Senpou Jinton technique. The Jinton came from Shukaku's chakra, so where did the Senpou, or Sage Art, came from? Naruto's Six Paths power.
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Sasuke said "I'll use the Six Paths' power too..." Too means "as well or the same", so he's the same as Naruto. Sasuke isn't using Jinton, as that came from Shukaku, so he has to be using Senpou as well, since he's doing what Naruto did, which was Senpou from the Six Paths power. Sasuke just called it the Six Paths' power because, as he expressed before, he doesn't understand what Sage Mode and Senjutsu really is. It's not Naruto's own normal Sage Mode because he lacks the markings around his eyes, it's from what the Sage gave him, and Sasuke got the same just in Yin form.
Orochimaru states here that his Curse Mark have Senjutsu in them.[
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] Curse Seals were created based on experiments on Juugo's clan's ability[
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][
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][
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] This means that a user of a Curse Seal is being influenced by Senjutsu. When using the Cursed Seal's senjutsu influence, Sasuke's Chidori turns black. This further reinforces that the Six Paths' power is a form of Senjutsu because its influence did the same thing to Sasuke's Chidori.
Jugo's clan absorb Nature Energy naturally through their skin[
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], which causes their transformations. Jugo's chakra is naturally infused with Senjutsu, so infusing it with Susano'o creates a Senjutsu Susano'o.[
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]
This is more than enough proof that the Six Paths' power revolve around Senjutsu, and that Sasuke isn't using it.