I've never seen "It!..." so this'll be a treat.
Yes, I've read articles and discussions about the similarities between "It!..." and "Alien" some 21 years later. That's particularly why I want to see it, to see how close the latter resmbles the former. I think the core comparison is the motif of a monster picking off crew one by one while secluded aboard a spacecraft.
And rather interesting "Them!" follows "It!..." I've also read comments how "Aliens" (Cameron's sequel) resembles elements of "Them!" You have the orphaned girl, monsters that are "colony" creatures, the rescue of a child, and the pursuit through a labrinth of tunnels with a flame-thrower.
Plus, it'll be fun to see these in high-def now that DirecTV is supplying TCM's HD feed. (I was stunned to see how good the original "Invisible Man" with Claude Raines looked when aired last August.)