It's tough. Because the ads will pay pennies. Unless your affiliate or products sell and become hit with good enough manageable numbers. But that is hard to do with a dog blog. But it's doable when you are the middleman.
For example, a blog about WordPress tools is awesome. Because you are blogging to website owners. Who will shell money to get the tools you are reviewing or selling. Compare that with a blog about college life. Your readers don't have money to buy any products you can offer.
Choosing whom you will target is the most important thing before you write even a single word.
The Maths Behind Million Dollars:
The time frame is important. Let's go for 10 years. Because $1 million in retirement money.
This translates to roughly $100k per year. Which is $10k per month.
If you can convince your blog readers to become a paying subscriber for $10 a month - all you have to do is convince 1000 of them. And in 10 years, you would have earned a million dollars from your blog.