On my husband's left foot he crushed his heel & all the metatarsal bones. Is he going to have problems with walking and balance?

He might. A fractured heel bone is a devastating foot injury, and with other bones involved more so. Arthritis and deformity can arise from this, and might require further surgery, bracing, and other measures. Talk to his foot ; ankle surgeon as to what his longterm issues might be. Good luck.
He should be seen by. An orthopaedic surgeon, who will reconstruct ; fix his fractures. Typically, prognosis depends on exact type of fractures, and which one extend into joints. These types of injuries may increase the risk of him developing post-traumatic arthritis in his foot, ; in some patients may lead to need for fusion of some of the foot joints. It should not affect balance, but may lead to gait pattern changes.
Injury. The main concern is the heel bone. If he crushed it, probably will develop subtalar joint arthritis in the future. This can be very complicated to treat but hope for the best outcome.