The terminator is at its core a story of anti establishment, rebellion, and hope for the future in the face of technological ruin. Here are a few things classical cyberpunk that terminator has

Cyborgs and high tech
– t800 is specifically called a cyborg canonically

Ai and control
– which spawn from skynets corporate greed, corner cutting, and misuse of high tech

Anti establishment
– anti capital/ anti corporate resistance is foundational to cyberpunk culture

Terminator isn’t only a cyberpunk piece it’s actually a crown jewel – because it shows the outcome and acts as a cautionary warning of the dangers present in cyberpunk works. So I’d consider it a Late stage cyberpunk/ dark sci-fi work. What do you think?