Hey Rahul! Those are two really big questions you have there. I'll try to offer a few practical pieces of advice.
How can I make a popular online presence through writing blogs?
Ultimately, you have to write content people find genuinely interesting enough they want to share it.
Often, I find that talking about your own experience in a way that people can apply your learnings to their own life does very well. It's unique, personal, and practical.
How can I monetize my audience?
Instead of thinking about it like "monetize my audience", I'd suggest thinking of it like, "How can I create something so useful that people will want to pay for it?"
Yes, you can use passive methods like ads and affiliate marketing. For a number of reasons, I don't think this works very well for a developer audience / technical content.
Instead, I would focus on learning what people in your sphere are struggling with and find out how you can help them.
Hope that gives you some things to think about!