Be thankful,remove them, and then plant something more attractive and hardy. Sorry, a bit harsh, but I hate 'em! To answer your question, if they're still looking good, then it might be possible to stake them, but it may be that you have to cut them down by about half, or even more,and wait for some latent buds to shoot out with new growth. I've just removed some that had collapsed, as they were too tall to stake sensibly. I've replaced them with pittosporum, which I love, and an aralia, to match the height and singular ugliness. Consider, too, pseudopanax ferox, similarly odd, but beautiful. Worthy

I'm not averse to tall Cordylines myself, so my advice will be slightly different to Worthy's above, lol!
Do nothing now - you will have to wait till spring at least before knowing whether your cordylines have weathered the winter well or not. If you see any sign of sogginess to the main stems, you will need to saw back to healthy 'wood', or wherever new growth is appearing from, but not now. You might find they recover and grow away from the top, or you might find they shoot from the base, or halfway up the trunks and the tops have died, but only time will tell. In a severe winter, they can be killed completely, but more usually, they shoot from the base or, if you're lucky, higher up, and can be cut back to those points - but not before end of May. So its a wait and see I'm afraid.