Silicon has a bonding capacity of four while sulfur has a bonding capacity of two therefore silicon with its higher bonding capacity will become the central atom with sulfur on each side. With sulfur's bonding capacity of two, it will need to form double bonds with silicone in order to satisfy its bonding capacity while being double bonded to two sulfur atoms will complete silicon's octet and also satisfy its bonding capacity.
It's lewis structure will look something like this but with two lone pairs on each sulfur atom.
S :: Si :: S