I think there's 2 things that kill Fox shows, and why I think Dollhouse may do well:
1. Is there a high production cost involved?
I would think that Dollhouse is going to have less costs than, say, Firefly and Drive (two shows that were good but got axed well before their time). Dollhouse will likely have a few 'high tech' looking sets and will need new sets/locations on a regular basis for different 'fantasies', but they aren't going to need as many visual effects as Firefly or Drive, and they aren't gonna have the stunt work overhead that Drive had.
2. Can they clearly market the show?
Using the comparison to the same shows, Drive was highly marketable as a car racing show, but had no major star to 'anchor' it, and I think Fox had next to no idea of how to market Firefly. I think Dollhouse is highly marketable as a futuristic action/sexy show, and Eliza Dushku is a fairly well-known quantity. Even Tru Calling, which was a non-quirky show about dead people, lasted over a season - it's only quirky shows about dead people that seem to succeed nowadays...see Six Feet Under, Dead Like Me, Pushing Daisies, etc (although Ghost Whisperer, which is almost exactly the same show as Tru Calling, is now on Season 3).
I don't trust Fox to do right by this show -- they are proven morons for most shows -- but I think Dollhouse has a much better chance to succeed than other shows that have met their premature demise.