Three people survived it, if you count Voyager. In one episode a woman who escaped the Borg said she was assimilated at Wolf 359. As I recall, she said she was on the Rosevelt. But it's unclear how she survived. Her being there makes ZERO sense. Another Voyager fuck up where the writers didn't seem to care what they wrote.
BOBW did the same thing. It was never explained in that episode what happened to the Jouret IV colony and its inhabitants or what happened to the crew of the freighter that alerted the Enterprise to the Borg's presence.
Most likely, after they destroyed the armada and assimilated some of the survivors in the lifepods or people they beamed off the ships (why not?) the Cube loaded them onto one of those Escape Spheres the Cubes have and sent it back to the Delta Quadrant.
We know there were other Borg vessels in the Alpha Quadrant after BOBW from "I, Borg" and "Descent" and that the Borg had created conduits for quick travel between the Alpha and Delta Quadrants from "Descent". It all adds up that the Borg could assimilate people at Wolf 359 and send them away.