First of all, I doubt anyone would be capable to conduct a survey in this chaos. So I don't know the exact number. But I do have found some videos in which the public express frustrstion and anger that the protests have affected their daily life.
The videos are in Chinese. And the first one has English subtitles. I tried to find the other two with English subtitles but unfortunately I can't find them under any search in English. If I have the time I'll provide a translation.
p.s. Since you said in the first paragraph that you are not surprised about some support the protesters received, I assume you have seen a lot video/news in favor of them, so I didn't put any of that here. Also the ones I find that are pro-independence are actually made by protesters and I don't think they are classified as "not involved in the protests" as mentioned in your question.
update 1: Translation of the third video:
You are doing fake news. You are biased towards them. If we use phones to photo them, you criticise us for doing so. But it's ok for them to photo us? And it's ok for them to yell at us, why is that? Are you or not biased against us? It's ok for them to beat up cops? Isn't that absolutely lawless? Are you in favor of them?
Even if you are filming me now, I know that you'll edit out whatever I have to say. All I can do now is to talk some sense to you, all by myself. I hope you think this through, think about what you are doing. You are just a pawn of those foreigners. Making a mess in Hong Kong won't do any good.
I am an absolute native Hongkonger, I was educated in Hong Kong. Why do you do such things to mess Hong Kong up? If you don't like it you can just leave. (followed by a sentence I don't know how to translate) Don't contradict me. I am only one person, what's for you to be afraid of? (In case not reflected by the transcript, this is said after she was condicted by someone, probably the interviewer or a protester, and was intended to imply the cowardice of that person) I only said a fact. Look at yourselves, absolutely lawless and orderless... (Some protests come near her) Come on, come and take a photo with me! Why the mask? Why the hat? Why the umbrella?