In the final shooting script Ripley blasts the Alien out of the wall with the flamethrower, it advances on her through the flames, Ripley opens the hatch and it's shot into space - but moving at the same speed as the shuttle just behind it. She fires the thrusters and the Alien is "incinerated".
Despite the differences between the above (October 1978) and an earlier draft (June 1978 - below) and the final film, it's safe to say the people making the film wanted the Alien to be dead. The final film can be interpreted as the Alien being dead or simply neutralised as a threat to Ripley.
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EXT. OUTER SPACE
The burned mass of the Alien drifts slowly away.
Writhing, smoking.
Tumbling into the distance.
Pieces dropping off.
The shape bloats, then bursts.
Spray of particles in all directions.
Then smoldering fragments dwindle into infinity.