Survivor? original? Or numbers matching?

It's subjective. To me:
"Original" means just that. Original. It retains the stuff it came with when picked up from the dealership including paint with regular maintenance and minor repairs excepted. A 1972 Duster car that had everything as delievered, but worn, and with a Holley carb added rather than a Thermoquad on it - is no longer 100% orginal. A car that had the passenger's side repainted because they wiped along a retaining wall in 1973 - is no longer 100% original. A car is original only once. Also note I said as delievered - not as ordered. Dealerships changed a lot of stuff, and repaired damage many owners never saw prior to the buyer taking ownership. A survivor car would be in this group too.
"Numbers matching" means those items that have the ID number assigned to them all match. The stampings on the body, the engine, and the trans for most cars. Using the same example a '72 340 Duster with that Holley could be "numbers matching" - but not "Original".