I've been told that the failed servo can lead to no pressure at all in your brakes, but losing all your fluid... not sure.

I guess it's possible that there was a serious failure inside the servo and the vacuum sucked the fluid into your intake. However, I'm not sure what happens to your engine behavior when you burn a cup or two of brake fluid in your cylinders. I would guess that the car would run poorly.

I'd recommend that you refill the reservoir and work your brakes for while. It's a bit more likely that you have a failed brake line somewhere or you're losing at the calipers.

I can just about guarantee that everyone else that posts a reply will tell you to get rid of the servo and get something better. They seem to be quite hated in here. I believe that you can have the servo repaired, but it's costly. You'd probably save money if you got a lockheed unit or worked out a mod for an aftermarket pancake-type booster.