Content creation can be categorized according to the title. If you are writing about automobiles, you are targeting the car owners. If you write about food, your target audience would be the new housewife, the hobby chef and gourmet cooks.
If there are 500 people reading daily, you can expect 345 people to have cars. Similarly, you can expect 400 people to show interest in food.
If you write about stamp collection, or water color painting, you will not have too many readers. (Just for example, you will have around 50 people).
You see how content influences number of readers. Within each category, there will be subclasses. Say, your are writing about garden. One section of the readers will have interest in maintaining the soil, while yet another group will want to know which flowering plants will be suitable for you them.
The only way to find out how many people are reading about flowers and how many are interested in the soil is to have an interactive section. For instance, you could provide a comment box or an opinion poll. Even if only one in ten people bother to vote or comment, you still get a fairly good idea of the interests of the readers.
Over time you learn to flavor your blog to cater to the long term readers alone. That is when you will have a steady following. Building up a readership base helps develop blog ranking among search engines.
One last point. If you need to migrate to another site, you might have to change your niche topics if you want good readership. Instead of writing about gardens and food you might have to write about fashion and handicrafts.
