Akatsuki is after the kyubi. "that person" is a translation error, as obviously the demon fox isn't a person.

He's saying "Akatsuki is after a certain person."

Then your quote comes in: "and that person is the "nine tails" isn't it? Are you sure of this?"

"It's very likely. It's chakra is one of the strongest. After all, it is one of the Youma"

The Youma are the legendary demons of which the kyubi is one of, if not the strongest, not sure.