A federal judge sentenced 30-year-old Antun Lewis on Friday.
The fire killed 33-year-old Medeia Carter, four of her children and four other youngsters attending a birthday party in May 2005.
Authorities say Lewis was upset over a drug debt and doused the three-story building's first floor with gasoline.
Lewis knew some of the victims. He asked the judge for mercy and expressed condolences to the victims' families during the sentencing hearing but said he didn't commit the crime.
Lewis was deemed ineligible for the death penalty because of mental disability. AP