It would really depend on Tony's love for his family.Even though Tony is really not a decent human being,he might take a jail sentence to give Meadow the chance to achieve her goals.She is really the only bright spot in the immediate family. Carmela has no ambition and no future, and A.J.'s career path and lack of any employable skills will land him in a middle management position rigging carnival games. Meadow is his little girl,and a constant source of joy. To rob her of a future by making her live in hiding would kill Tony,and I believe that he would sacrifice his freedom for her.
On the other hand,if Tony does flip,I see him having no problem looking Sil right in the eye from the stand.

If Sil decided to rat,I think he would do it as a practical decision. He is usually the coolest head of the group and if he did flip,I think he would have a major problem looking Tony in the eye as he testified.