Desconhecido.
Parece que o destino de Orac nunca ficou claro:
Orac was damaged in the destruction of Servalan's base on Terminal but repaired. Not long afterwards it recognised the dangerous nature of Muller's android but was still taken over by it. It was damaged again when Xenon Base was sabotaged. Avon kept Orac with him when the Scorpio was shot down over Gauda Prime. Orac was not with the rest of the crew when they had their final encounter with Blake; its fate is unknown.
-- Blakes 7 Wikia, emphasis mine
Orac was not present during the final shootout on Gauda Prime in Blake, and his survival or whearebouts are unknown. [...]
In Paul Darrow's canonical Lucifer series, Orac is later retrieved by Avon and used to find ways to stay alive and find ways to fight The Quartet. In the last novel Orac is used as a last resort to kill the guards with an explosion and tiny metal darts destroying itself in the process Orac later calls out into what can only presumed to be the afterlife for Avon. However Avon either doesn't reply or cannot and the novel ends with Orac weeps for his friend.
-- Wikipedia, emphasis mine