Is it possible to become a researcher in Artificial intelligence through a statistics phd? Or is a computer science phd required? Is having a statistics phd a disadvantage for AI research positions or does the research you publish and work on during the phd matter more? 

Although artificial intelligence research is interdisciplinary (math+cs+stats+logic, etc), I see mainly computer scientists working as AI researchers in industry at places like Google Brain, Open AI, DeepMid which makes sense since AI is an area in CS. Is it more because statistics phds aren't interested in working in AI or are these positions are mainly for computer scientists?

I am deciding whether to accept a statistics phd from a top school where a lot of good AI research is happening and the CS and stats departments are traditionally close. I believe I could work with an advisor who is in both departments or have one advisor in the stats department and the other in the CS. 

Thanks!
Nobody cares what species of PhD you have.
If you publish research in machine learning venues, you are a machine learning researcher.
In particular, if you publish good research in good machine learning venues, you are a good machine learning researcher.

Just at my own university, I can think of machine learning researchers with PhDs in computer science, statistics, applied mathematics, pure mathematics, computer engineering, electrical engineering, mechanical engineering, astronomy, linguistics, library science, operations research, aeronautics, and economics.  I'm sure I've missed a few.  They all do different types of machine learning, but whatever.

The correct question to ask is Will a statistics PhD from [department] working with [advisor] support my ambition to work in machine learning?  And the answer to that question depends on [department] and [advisor].