As it has already been explained in this thread Spartacus winning was unlikely, improbable. And I wholeheartedly agree.
One thing for sure - Spartacus could not take the city of Rome. No way. Even Hannibal did not try it.
So best case scanario for Spartacus was escaping from Italy with his army. His escaping to Spain or to Bosporus were discussed here.
But there was another possibility which Spartacus tried in vain - getting his army to Sicily. That was quite natural for him to try.
Sicily was the place of
the First Servile War of 135–132 BC and of the
Second Servile War of 104 BC-100 BC.
There was a great concentration of slaves on this island and the most cruel way of slavery - plantation barracks' one.
And during these two Sicilian Slave wars the slaves managed to create something similar to Hellenistic statehood.
Spartacus might create his state with the centre in Sicily which was fabulasly rich in agricultural products and most definetely self-sufficient. The island was relatively easy to defend.
Spartacus would found his dynasty. One of the necessities for this young country would be a strong navy so he might try to take Corsica and Sardinia or at least raid them together with Cilician pirates.
Spartacus would play a role of coordinator of all anti-Roman forces: from Bosporus to Spain; succesfull Spartacus is impossible without succesfull Sertorius and Mithridates.
Of course there would be nothing like a 'socialist' state. That would be quite a usual hellenistic monarchy. The former slaves would be proud owners of the slaves themselves.
I would give this state 10-20 years of life untill the Romans recover and beat all their enemies including their former slaves in Sicily.
But Spartacus might found a new tradition in international politics of the Mediterranean - all the forces ally against a bully who is about to threaten the fragile balance of powers.