A better translation could be :

His relatives are scared that he can be tortured if he is sent back to Uzbekistan…

Soit is the subjunctive of être. Craindre, that is used in the main clause, is one of the verbs expressing fear (or doubt), that require the use of the subjunctive.

To say his family were sure we would use the indicative (and a different verb) : ses proches savent qu’il sera torturé.

Ne in this sentence is optional. It is not part of the negation but it is often used after craindre in formal written French. It is called ne explétif. You can read the answers to this question on French Language aout the ne explétif.

Google translation could be better since “will” does not show the action is uncertain.*

* _{I would say: “They fear he might be tortured if returned to Uzbekistan”}