Communicating

Telling him over and over is not the correct approach - it will only reinforce the fact he can ignore you. He's 7, not 17, If he really needs a bath, pick him up and take him into the bathroom, and let him choose some toys to play with while you run it. Use bubble bath if he likes that, or get a bubble blower for him to play with in the bath, to make it more fun. Don't accept no from him - you are the parent. Children need structure.

However, if you are expecting him to have a bath every day, also consider whether he really needs to bathe that often. As AuTriker said, years ago (When I was little) we only had a bath once a week. Maybe 3-4 times a week would be a better idea.

7 years old is usually the age children start to understand days of the week. If he has reached that stage, you could mark a calendar or chart with "bath time" or a picture of a bath, plastic, duck, etc, so he has a visual prompt of when he will have to take a bath. If he doesn't understand that yet, you could stick a bathtime related picture up somewhere (maybe on the fridge with a magnet?) on bath days.

When I was a kid it was bath night once a week, that seemed doable, I cannot cope with this modern idea of doing it every day! As it is so intensely sensory, once a week it can be a pleasure, taking one's time, maybe read or as a kid play with toys in the bubbles. But every day would just be too much and I would resist that. 

But no your husband was not taking the right approach! When people try to force me it makes me dig my heels in. I can be persuaded and reasoned with, but it does have to be reasonable, like once a week. Giving options for some degree of autonomy also helps.

i always hated baths or showers as a kid... was always time consuming when i wanted to play games or do something else... plus when you get out your freezing cold. plus then with showers the water always got in your eyes.

its just normal i think. when you get older you then shower more as you are more aware you may stink. although it still is a thing where you just cant be bothered and it takes too much time you dont wanna spend.

I think lots of children hate having a bath or shower, not just those with ASD, if he says no, then you'll have to put your foot down and make him, try the suggestions above because you don't really want to scare him, but you are the parent and you have to impose discipline every now and again.

try asking 'would you like to have a bath tonight or a shower instead?'

this gives your son a feeling of agency and control which is something he definitely he would like to have. Make it sound like you are eagerly awaiting his command as to whether it will be shower or bath and when he says which one, congratulate him on the wise choice he made.