will these ducks survive the winter?

Releasing non-native ducks into the ecosystem is illegal. Your friend is an irresponsible idiot. No one should dump pets ever!! If she could not keep these ducks she should have found homes for them or at least given them to the humane society or a local rescue. Hard to say if they will survive. They might die or be eaten by a predator.

You don't say where you are living.

But there are a lot of locations from which birds would naturally migrate, if they were not fed by humans.

The first reason birds migrate is for food. Cold weather in the winter cuts down on the amount of natural duck food, so the ducks migrate south to find enough food.

Often in cities, though, people continue to feed the birds and they will not migrate. I have seen this when I lived in Seattle. Geese, ducks, seagulls, and starlings, among others, would normally migrate south for winter. But the ones living in the city will often stay all winter because they can find food left by humans, accidentally or on purpose.

If other ducks are spending the winter at this lake, then there is no particular reason your coworker's ducks won't do as well as the others.

if they are still adolescents, they may have hope of flying. And if the existing herd accepts them, warmth should not be a huge issue. Predators will be a main issue if the ducks were raised in a captive,closed environment (i speak from experience, my ducks were killed by a fox and a hawk)

your coworker should rethink it next time they consider trying to keep ducks

Ducks and geese have "down" the kind they use in coats and blankets. It's one of the best insulators known to man, so I believe they will.

there are several little ponds that i see many geese and ducks at durring the winter im sure they will be fine