You can see the excerpt and more details about it on the Locus Online website
. Here's a small excerpt from that website:
"I wrote The Diviners because I wanted to write another series, something historical, but also supernatural. I’m a huge horror fan. That was my reading of choice when I was young – I read everything from horror comics to Stephen King and Shirley Jackson..."
It seems like you have to buy the magazine to read the entire interview. If you go to http://www.locusmag.com/Magazine/2013/03/april-issue-table-of-contents/
, you should see a link on the right side to buy the magazine or the digital version.