I don't know if this helps but I have found that having a gentle approach in guiding people towards less animal consumption has worked best for me. By introducing people to healthy vegetarian/vegan meals, and living and being healthy without preaching goes a long way.

If you're going to shift their attitude about animal cruelty, be a good role model to those around you. Most of us are aware of animal cruelty on some level already. Maybe some people will get the message by the health benefits, and others on the fence might be inspired by your courage.
Even if you don't manage to change peoples minds right away, at least they will have been exposed in a positive way to an alternative.