The animator confirms the name, but states that the author is still ironing out the abilities. Jougan literally means Pure Eye. Toneri talks about the Jougan in relation to the Nue, which was what stimulated Boruto's eye in the first place. What more do you need?
If it's not then what is it?
SharinGAN ByakuGAN RinneGAN TenseiGAN JouGAN, can't get any more straightforward than that.
Imagine being as dense as this guy.
It's a dojutsu confirmed...
But I mean, let's take a deeper look into it. Toneri knew that Nue was released from Kaguya's dimension. He also knew that Boruto's dojutsu was activated. He came to Boruto in a dream. So, when he had his monologue at the end of episode 15, wouldn't it have made sense for him to say, "Jougan's turn won't be coming
AGAIN for some time."? He mentioned Jougan as if it would be his first time making an appearance.
But wait... if Jougan was Boruto's dojutsu, why would Toneri make it seem that Jougan is making an appearance for the first time if it had already made an appearance.
What Toneri said: "Jougan's turn won't be coming for some time."
What Toneri should have said if he was referring to Boruto's dojutsu: "Jougan's turn won't be coming again for some time."
You guys have to read between the lines, dissect the dialogue/monologue.