Could aliens survive in deep space?

The short answer is: probably not as active, free-living organisms, but possibly in dormant, shielded, or non-biological forms.

Deep space is extremely hostile: it has near-vacuum, intense radiation, and no readily available liquid water or food. That makes ordinary metabolism, growth, and reproduction very difficult for any life as we know it.

What could be possible is survival in a dormant state or inside strong shielding. For example:

• Microbes or spores protected inside rock, ice, or debris
• Life with extreme radiation resistance or very efficient repair mechanisms
• Life using a different biochemistry, if it exists, that tolerates space conditions better than Earth life
• Technological life, including machine intelligence or spacecraft-based habitats, rather than biology alone

We do have examples on Earth showing that some life can endure space-like conditions for a time:

• Tardigrades have survived exposure to vacuum and radiation in space experiments
• Deinococcus radiodurans is famous for surviving extreme radiation by repairing its DNA
• The panspermia hypothesis proposes that microbes could travel through space inside comets, asteroids, or meteorites

So the best answer is: aliens could theoretically survive deep space if they are dormant, shielded, biologically unusual, or technologically supported, but active unprotected life in open deep space is extremely unlikely.