As a defacto D&D standard, every combat is winnable somehow and being captured by bad guys is a one-way ticket to losing all your cool loot.
Given that, the answer entirely depends on the campaign to date. I chose "few would surrender" assuming that this was the first encounter of a campaign.
I would expect that many D&D campaigns (or rather, most D&D DMs) would need to have encounters prior to this establish that:
a) There isn't going to be any DXM saving the PCs if they choose to fight (ie - previously the characters have gone up against unbeatable forces and lost, and it has cost them)
b) When you surrender to a foe, it furthers the game (ie - there have previously been incidences of capture where the rescue/escape have been fun experiences)
in order to coerce a willing surrender, no matter what the odds against the party, or the trustworthiness of the captor-to-be.