Yes those are heating cables, they will be covered with pinned insulation against the concrete. The soffit will be a cold space, cables turn on via thermostat. Not necessarily a "heated floor" above, but there to make sure you dont feel the cold during winter. Here the concrete is what 5-6 feet thick? Cant see much heat or cold migrating up, will keep slab warm tho.In those photos above of the 'undercarriage' (my term) of that overhung part, it sure looks like there are heating coils for a heated floor there. Anyone in the know feel free to correct me if that's not right.