Some industries are indeed barred from certain provincial nominee programs, but in order to assist you we would have to get a better sense of the program you are interested in. That said, restaurants or small hotels can be acceptable, but the acceptability of the file will largely depend on the business plan and thoroughness of the application submitted.
What field of business has a higher possibility of getting a provincial nomination in Canada?
After consulting with a migration agent, I was told that businesses like restaurants or small hotels have less of a chance of getting a nomination. Is that true? Are businesses in innovative and high-tech industries more likely to receive nominations?
Your migration agent seems right. And your assumption is right too: Any business that brings something new, fresh, creates jobs (and, at the very least, maintains some jobs) is good for Canada, hence increasing your chance of a nomination.
High tech is welcome in Canada.