These people are not like us. They're more like sovereign corporations with a pseudo-monarch as head, and a literal army of both overt and covert support workers handling security, PR and impression management, financial operations, and so on.
Social media bot accounts are possibly the lowest cost and highest return form of PR and sentiment management ever invented.
I personally suspect that his army of stans is large enough he doesn't need shills, but it'd certainly be a huge story if they could prove he was funding shills.
(There are definitely a LOT of ~"@elonmusk59393259" fake accounts pretending to be him that try to pump coins or offer fake giveaways, but I don't think he's done so himself?)
True shilling feels significantly more morally repugnant than these sorts of 'coattail-riders', but their impact is certainly similar.
"Shills" implies commercial backing. Ex. the democratic party hires operatives with shill account networks to create the illusion of popularity for certain tweets. (google sally albright)
"Stans" is the better term for Elon fanboys. I haven't seen any evidence Elon is paying these people to defend him online (would be pretty pathetic if he was). I think most of these people are just really into the cult of personality. Much more similar to kpop stans. (etymologically rooted in the eminem song "stan" - an excessively obsessed fan)