I think one alien compliments a survival horror idea much more so than many aliens, and it would be very difficult to pull a survival horror game with lots of xenomorphs in a setting such as this.
In the movies, Alien (survival horror) had one alien and it was great with almost no weapons; Aliens (action movie) had lots of aliens along with hard-core firepower.
There's pluses and minuses to both. There's more shock value when you can't use heavy weapons, even if there's just one monster., but that wears off after the first play through because then you know how to get past it. If the only trepidation is having to know where to go and when, then just wait, it becomes boring AND repetitive. Most survival horror games are only good for one play through because of this. Amnesia for instance was open to player generated scenarios to try and compensate.
With action type horror games you usually have suspense generated more from ammo and weapon management and surviving waves, which can be just as scary depending on how they equip you. Some have stealth opportunity as well though. They pretty much HAVE to equip you well enough though, and once you know where to get ammo and supplies and how to conserve them, the suspense is traded with the clear and repeat syndrome.
I really feel either style can be good or bad. The problem is, no one really scales these types of games very well for all levels of players. Sure they do things like limit supplies and ammo on higher difficulty levels, but usually not enough so. The Metro games are a prime example. They attempt to offer both survival and action styles, but I feel they equip you too well and the AI is not good enough. They're too easy even on Ranger Hardcore.
And there's ways to scale the AI too. They could make the enemies adapt to what you're doing, like Mr Freeze does in the boss fight with him in Arkham City. You can try each attack method only once, successful or not. This adds variety and suspense, and makes battles considerably more lengthy and engaging.
Another way you can make either style of game more elaborate is to rotate spawn locations and patrol routes of enemies, as well as those of ammo and supply spawn locations. Scaling density of enemy spawns to how the player is faring can also work, but I feel that is one area both Valve and Overkill failed when it comes to solo play. L4D and PayDay are best played coop, because solo is too chaotic and the AI are too inadequate. I would REALLY love to see these ideas used well in a true solo game where you're by yourself most of the time though.
Elaborate AI and scaling difficulty levels either by fixed design or on the fly methods is an art few have done well.