What is the life expectancy of someone with hemophilia?  

Near normal. The disorder can be of varying severity, but robust treatment options are available, including recombinant drugs and gene therapy. If severity is low and resistance to drugs do not develop life expectancy is near normal.
Hemophilia. With modern treatment, most patients with hemophilia should have a normal life expectancy. Things to watcfh for include HIV and hepatitis infection, debility from joint disease (if type a of b hemophilia), and coronary artery disease.