How much traffic to expect by article writing

The traffic doesn't come from article writing. It comes from article reading.

And that depends on where and how your articles are published. (But it hardly depends at all on how many of them there are).

Article directories are not a traffic source.

No article marketer wants potential customers to come to their site via an article directory. We all lose most of that traffic.

This post (with its links) explains how article directories work: How do Article Directories work?

This thread from the last day or two explains in more detail about what you're asking: question about article marketing?

It depends how well targeted the traffic is, and what you're promoting. If it's a highly relevant, information-packed e-book for $3, you might sell a lot more than that. If it's private jet hire, your conversion-rate may be a lot lower.

"How many articles" is never a good question, I'm afraid. Success in article marketing has very little to do with the number of articles and everything to do with who reads them.

I sometimes get thousands of visitors and hundreds of opt-ins from one article, like this: http://www.warriorforum.com/main-int...ml#post5035794

But you can also very easily put 500 articles in 1,000 article directories and not make a single sale at all from it.

The people with the highest numbers of articles (some have tens of thousands in EZA and elsewhere) are not doing very well from them, and there are reasons for that: they have a quantitative approach that doesn't work.

It's just not about "how many articles" (and for article marketers, that's really good news).