A Cutter with class 6 Prismatic shield and 5 boosters is fairly safe and I'm confident it can survive an attack from any SINGLE ship.
That said, if you get attacked by a well organized wing, there is very little chance of delivering any cargo. Several times I got chased out of a system by a wing of 4 Vipers - they don't deal much damage but a wing can easily keep chain interdicting a ship and effectively prevent a ship from reaching the destination, even if they can't destroy it. And any ship will run out of shield MJ and hull given enough time.