You can keep them alive until spring with or without a grow light, if you have a good widow. If you want fruit before spring, and if you want them stronger, I recommend a grow light. If they grow too big, you can take cuttings and root them for new/additional plants. If you're running on window light, you should realize that the time of day in which the sun produces the kind of light that tomatoes like the most may change in winter. Where I'm from, they like the east morning sun in the summer and fall. In the winter, they like the afternoon sun (they grow toward the west instead of how they used to grow toward the east). So, be sure to position them in the window according to the light they prefer. If your windows are east/west instead of south like mine, you should move them to the window they prefer at the proper time of year. For a south window, if you keep them in one spot all year they may suffer if they're not near the middle of the window.
I've never heard anyone talk about the east/west change from fall going into winter. My plants just showed me within three last few months up until now by their behavior. The ones on the west half that receive morning light (and low afternoon light) definitely need to be moved, or else they need a grow light. I've got a few on order, though, but I just moved the plants (and edited this post to reflect that).
You should be able to get lots of tomatoes next year due to larger and more mature plants. When you plant them in spring, you could plant them really deep so as to give them more nutrients and drought-resistance. They should grow roots all along the buried stem. Your plants, and even the cuttings should produce earlier tomatoes than usual, too.
Be sure to use clean soil for cuttings to protect against damping off or root rot.