Blogging signals to the world that you know what you’re talking about. If your content is good, it raises your trustworthiness as well. These things increase the chances of people buying from you (also known as conversions).
The exact amount depends on the quality of your content and your industry so it’s impossible to put an exact number.
Think of it this way…
Spam vs. Trust
There are two extremes of buying situations. On one extreme you have pure spam. For example someone just pasting buy links all over the internet. On the second extreme there is your mother (best friend or someone you trust) who tells you to buy something.
In spam example, you are most likely never going to buy whatever was offered that way.
On the other hand, a recommendation from your mother has a significant impact on your conversion rate.
Blogging allows you to move more towards the trust side of your potential customers. And the more trust you have, the higher the conversions will be.
You can learn more how blogging can grow your revenue in this article: