This is Purely Dependent on your website positioning in Search Engine and what is the niche of your website. If its very Famous then i dont see any reason for less number of visitors
It depends on many things. arcade sites might get more visitors on the weekends, but sites for SEO companies might get less traffic due to less people working on that day. So it all depends.
If your site content targeted to business habit then yes your earning would be slower in Weekends/Holidays. But if your site content targeted to what people are looking for in their weekend (travel, games, etc.) then holidays is yours.