According to the Wookieepedia page for List of Legends elements in the films:
“…we’re inspired by the comics and the books…” ― George Lucas
so it sure is a possibility.
Is the old Marvel comic you refer to the Star Wars 68: The Search Begins?
I’ll have to try and get my hands on some of those old comics again, and give them another read. If that is the comic, then I remember it being pretty cool. So it would be a shame if that was the inspiration for what would become some of the lame execution for the Clones and whole Clone Wars backstory in the Prequels.
i also think he was inspired by Tales of the Jedi and Dark Empire Comics for the Prequels supposedly George helped in the creation of Tales of the Jedi
There is a really good article somewhere listing many of Tom Veitch’s contributions and ideas from his EU work that later made their way into the films and series. I’ll see if I can find it, maybe at CBR or comicbook, at some place like that.
I think the New Jedi Order also has some stuff in that Lucas was going to use, or was inspired by, for his unused Sequel Trilogy ideas too. I know next to jack about the EU compared to others, but these folks seems to believe so on the NJO stuff:
https://www.reddit.com/r/StarWarsEU/comments/hr1tnz/behind_the_scenes_the_making_of_the_new_jedi
Though more knowledgeable heads on here will know far more than me.