While you could armour the gondola, you would of course be trading payload for weight. Of course, there's always the unmanned option as envisioned for LEMV.
Already in the 'real-world' HAV and others fly these airships across the States and North America on a regular basis, where they are repeatedly shot-up by every hick with a firearm. Ive been told anecdotely that they often arrive at their destination peppered with bullet holes, and to date none have been lost to such ground fire.
Of course, a large part of surviveability is being smart as to where and when you use it. There are planty of platforms in service today that you'd think twice before deploying directly into harms way, and yet they all have a role to play.