The mass of the central black hole is a tiny fraction of the mass of the galaxy, it might be more correct to say that the objects in a galaxy orbit the common mass (including dark matter) of the galaxy.
For example, the black hole at the center of the Milky way is estimated at 4.1×10^6 M (solar mass) and the total Milky Way mass is estimated at 0.8–1.5×10^12 M (figures from Wikipedia).
Some interesting articles found while digging for these numbers:
https://ned.ipac.caltech.edu/level5/Merritt/Merritt1.html