as long as there are leaf nodes below the snap you should be able to get new branches. I had one snap at the base once and I took a quick cutting from the broken part and put it in a glass of water. Within a week it grew roots and I repotted it and still had enough time to get some tomatoes from it.

Make some fried green tomatoes and what do you mean snapped in half? If just some main branches snapped off they'll probably come back, just won't be getting the same yield.

You can stake and tape them unless they're completely severed, though the vegetation above the break will be sad for a while after.
If the break's lower down you may want to prune back a bit so the plant can focus on repair rather than maintenance.

I always put my tomato plants in a tomato plant cage. I use plastic zip ties or string to tie the longer branches to the metal cage for support.

It might not be too late to plant new transplants if you buy transplants, depending on your climate. You could just buy a couple new plants and put them in cages in the ground. You could ask your local plant nursery.

One time I went to this old man's house who has been farming for like over 80 years. He took me out to his shed and shows me this massive tomato plant in a bucket. He tells me that it's from the last year and that he kept it alive in his shed all winter as a joke. I helped him replant it in the ground. I'm not sure if it grew more tomatoes after that. The point is that tomato plants are pretty resilient.