They definitely can overwinter. And, in your climate that should be possible.

Couple of things:

• they don’t grow well over the cold months and go into a sort of semi-dormancy.
• pruning them heavily before spring seems mostly detrimental. they may try to push new growth which will suffer, and seem to benefit from a cloak of leaves/dead stuff.
• they don’t tend to do well in subsequent years. the center of the stem doesn’t become woody and instead starts to rot out. (I’ve done it several times. They have problems.)

If you end up with a plant with some viable shoots come January/February and you’re not expecting any frost, rooting some cuttings or layering from the original plant can give you viable starts for spring planting. (This probably makes the most sense in your scenario.)

If you plan on starting from seed, most places that sell starts get theirs going first week of January. They have a small seed and take a while, especially in cool weather, to get good enough size for transplant.

The other option is seeding in place, which preserves the native taproot damaged in the transplanting process. This can result in more vigorous plants, but can be challenging in terms of weeding and managing pests. (With you growing on a balcony, the benefits/challenges here might be minimal.)

IMPORTANT EDIT: Determinate or indeterminate: A hard frost murders all tomatoes. Bring them inside for the night if thats a risk.

Edit: Lo siento, mi espanol muy malo, pero: Alguno tomato no muerte, alguno muerte. Es possible sus plantas no produca comida durante navidad pero mas fuerte en verano. Ten mucho cuidado durante un noche con nieve o otro.

First, there are two types of tomatoes: determinate and indeterminate. The words mean exactly what you’d think in terms of life cycle. A determinate plant will grow, flower, produce fruit, then die. An indeterminate plant will keep living and keep flowering, although they sometimes need “cues” to flower.

If you’re plants are still alive my guess is they’re indeterminate, or a hybrid. They may not produce fruit over the winter but you’ll have a head start in the spring! You may need to pay extra attention to fertilizing though as they may have used up all the good stuff in that soil.

Also, check out some youtubes on tomato pruning. There are branches that don’t make fruit, and especially with an indeterminate, you can increase the yield by having a long living plant that you’ve pruned into mostly fruit baring branches over the years!

I let the last handful of tomatoes rot on the vine, this lets some seeds naturally get into the soil and start their journey. Early spring right before the end of cold weather, I take the old plant out completely, add pot ash, clear any debris gently, and allow the new seedlings to take over. This isn’t a sure-fire method, and may result in freaky mutant tomatoes on year two and beyond so do your research if you apply it. Good luck!

It depends on where you are, and what your winters are like. Where we are they’re already dead and gone, but friends who are closer to the equator still have theirs producing. There isn’t information in your post to give an accurate answer, but if you provided your location there would be more to base an answer on