Do you think this law suit by Kate Steinle's family will make the difference to change immigration polices?

I think it's great! If nothing else, it will keep the light shining on the cockroaches.

Change the immigration policy to what? Building a wall at the border? If the shooting in Mesa Arizona did nothing to change the immigration policy, I doubt that this will do.

There is a chance the suit could cause San Francisco to revisit its sanctuary city policy. This policy disallows local officials from questioning a resident's immigration status. It is unlikely to result in any meaningful immigration reform.