It depends , if you have more pages but content is not good then it doesn't count, but if you have quality content on them then definitely you will get good amount of traffic.
It depends on the keywords, and the competition for them, some keywords having lots of pages with hardly any backlinks will rank well, and others may not rank so well. But it is a good idea to have unique updated content, Google and the other search engines are looking for authority sites to show to their users
for me pages doesn't mean more traffic. it's really based on your content, keywords and how you promote your site
Going from 1500 to 70, 000 pages in just a matter of months? Doesn't surprise me that you're not seeing a boost in traffic. Most of those pages probably have junky, low quality content.
Yes,thats true.If your site has more number of pages,a visitor coming to your website will view and spend time on your site more and then like this your website pageviews will increase,also traffic and your earnings will also increase since you will get more clicks
yes more content mean more tarffic- 20 bad articles will still get more traffic than 10bad articles. however 1 good content can bring you over 250 000visits like my article related to dubai  alltopics.com/dubai-beach-hotels-leisure-and-recreation.html
Well, as for my points of view having more pages doesn't mean your traffic gonna increase. It's always on what your pages are all about, or does it catch your target viewers attention, or does it fills out your viewers needs. The bottom line here is that the quality of your works will drive more traffic and not the number of your pages.
Your pages have likely not jet made first page on Google SERPS. If they are hard to find, they will not attract more visitors.
Rather than Quantity look for Quality on the pages. Also the low quality pages may affect the total site. More Quality = More Traffice
You certainly have more chances of getting traffic but it depends on the quality and the keywords you have on the page. In large sites like yours most of the internal pages ranks for a certain keyword, possibly a LSI keyword as you are not directly backlinking for them. * Improving internal linking (cross linking) might improve your results, this can raise your overall value of the site on google as well. * If you have a few "great" pages, you might want to actively backlink for them and also link back to them from related internal pages. Ultimately, if have to have quality like others said.