Is it possible to fix a torn pectoral tendon after 4 years?

Unlikely. The muscle tears and retracts. Usually within a couple weeks enough shortening occurs that it becomes very difficult to reattach. After 4-6 weeks the fibrosis is enough that any repair would be very unlikely.
Probably Not. I am unaware of any surgeon who has attempted to repair a pec. Tendon that has been torn for 4 years. An MRI would be helpful in determining, as it would detect tendon retraction and muscle atrophy. Both of these would help determine the potential for repair.
Unlikely. Unfortunately tendon injuries have a limited window for good repair, usually within one week. After that the tendon retracts away from the muscle and scars down. It generally cannot be pulled back to make the connection.