My concern is that he is throwing a lot of attraction body language my way:
Ok let's go through these and see how you could be projecting here...
holding my gaze
Making eye contact
mirroring my gestures
Unless mirroring mutual masturbation you're probably just both using perfectly average, everyday gestures
repeating some of my words and phrases
Literally just polite conversation / discussing the same topic
hips and feet pointing at me during conversations
Aka facing you while talking to you?
eye-brow flashes
Moving his face when talking
using posture to make himself look bigger
Standing confidently
self-grooming
Touching his own face? Pretty common. Grooming you would be an actual sign.
removing his glasses when we have chats
I do that when because I'm short sighted but when someone's close I can see them fine
You have a crush. Maybe he has one on you too, maybe he doesn't. You're married and say you have no intention of acting on it. So I presume you're perfectly capable of speaking to him in a non flirtatious, normal, run of the mill, professional way? Good.
Can you see how problematic it is that you think if a man fancies you, then doing so (being professional) is 'leading him on'? It wouldn't be that you'd led him on if he made a move, it would be that he was a creepy sleaze who responded disgustingly to a woman being professional in the workplace.
If you aren't going to flirt with him or shag with him, don't. If he acts as if you are, tell HR or tell him he's wrong, inappropriate and unprofessional.
You're making this a big deal because you have a crush. Everything you've described him as doing that you're reading as him returning your crush is perfectly likely to simply be an adult being courteous, friendly and professional with a colleague / employee.
You want this to be a crush but also say you don't want it to be an issue. You're both married so it can't be a mutual crush without causing an issue really.
All sounds really teenage. The hips and feet thing is cringe OP, sorry, I think it's the kind of thing I would have read in J17 when I was in sixth form and made a mental not of when I saw a boy i fancied at the bus stop after school.
Chill - you have a crush, he is being normal, there's no need for any drama. Be professional.