Yes, it's shown clearly in the anime that
Sen Takatsuki is the One-Eyed Owl.
They started giving hints about it in first half of the episodes in Season 2.
Season 2 Episode 1
Kaneki joins Aogiri and is welcomed by this girl named Eto
Eto seems to like Kaneki
Season 2 Episode 2
Later on in the next episode, Eto removes her bandages and smiles while taking Kaneki's name
Season 2 Episode 3
In the next episode, we see this author Takatsuki and she smiles the same way as Eto while hearing Kaneki's name - Can safely infer that Takatsuki is actually Eto
Season 2 Episode 7
The same smile pattern after hearing Kaneki's story from Hinami. Takatsuki is Eto confirmed!!
Season 2 Episode 11
I think you missed this part. It was shown after the ED theme in Season 2 episode 11. It clearly shows that Takatsuki is the 2nd Owl, and the only daughter of Yoshimura (who is also called non-killing owl)