Way too little information - what is needed:

Type of heat:

a) If there is no power, a furnace with a blower will not work, full stop.
b) If it is an hydronic boiler with a circulator, it will not work, full stop.
c) Anything with spark or hot surface ignition will not work. full stop.
d) If it is a steam boiler with a standard vent hood, standing pilot, and a millivolt-style thermostat (which was common enough in 1965), it will work as always, as it does not depend on line-level power.
e) If it is an old octopus furnace (obsolete in the 1930s, much less the 60s) as above, it will work as always as it does not depend on line-level power.
f) If it is a gravity hydronic system, millivolt stat and standing pilot, as above, it will work as always, as above.
g) No oil-fired system will work as it needs mains-power to run the gun and the ignitor.
h) And, obviously, electric power will not work.

Even if you have installed a modern thermostat on a millivolt system - the batteries inside the stat should maintain function power-failure or not. We change ours with the spring time-change every year, even though it is for a mod-con hydronic boiler with three circulators. But if the batteries go down, the stat goes down.

Peter Wieck
Melrose Park, PA