Many thanks to Ayako for tweeting the link!
The 47 Ronin soundtrack will be released by Varese Sarabande on December 17, 2013. The following is provided about the soundtrack:
Composer Ilan Eshkeri’s (Kick-Ass) epic score offers a powerful and exotic mix of cello, percussion and flute with symphony orchestra, capturing all the color, action, emotion and drama of the story.
Additional information is here.