2727 Hours

Just running the maths, on if the battery CR927 running the ATTINY45 and the RV-8564-C2. On powerdown mode ~ 30 mAh / 11microA – http://wolfr.am/UlDHB4

Giving 2727 hours or 3 months, 22 days. But this is worst case for powerdown mode for the ATTINY45, but does the check for touch every 4 seconds or actual power used when the LEDs are turned on.  Assuming these things cancel each other out 3 months is acceptable.