What happens when a huge star in its later stage( iron core) is near a black hole that slowly consumes some of the matter from the star? Would this offset the imbalance caused by iron fusion prolonging/ deterring a supernova?
A large star near a black hole may lose some of its atmosphere by having it spilling over its Roche lobe and into an accretion disk around the black hole. That disk will also radiate significant amounts of UV and X-rays that can blow away more atmosphere. That could in principle lighten the star, lowering the pressure and temperature in the core, and extend its lifespan a bit. Usually the amount of mass lost is just a few percent, so this is not a big difference. However, as discussed in the first link, for some heavy stars significant amount of matter may be lost (especially since the star itself may radiate so much that it loses its outer envelope). It does not prevent the star from eventually going supernova, but can change what kind of object it turns into (neutron star or black hole).