Okay. I actually made a throwaway for this because while I would never actually use the term "internet famous," I'm sort of well known in my field. I'm going to ask you some questions to think about and give you some harsh truths here, based on personal experience.
Can you name three things about her that have nothing to do with her online fame? Why are you interested in her? If the answer is 'because she's cute/funny/sweet/internet famous,' you can cross her off your list because I guarantee you if she has any kind of "internet fame," there are plenty of other guys out there just like you that have a crush on her. Some of them tweet at her. Some of them probably talk to her. Some of them probably try to flirt with her. Most of them probably make her pretty uncomfortable because:
I don't know what this girl does or what she's "internet famous" for. But if it's for anything in the digital entertainment field, that Twitter account you're following - you know, the one with however many hundreds of thousands of followers - that's work. That's the metaphorical office. Guess how much fun it is to get hit on while you're at the office. Go on, guess. (Hint: it's not fun at all and honestly sometimes it's a little creepy)
When you tweet at her, does she make an effort to reply to you? Has she ever replied to you? If she has, was it an actual conversation, or just a throwaway comment? If she's interested in holding a conversation with you, she'll do it. If she hasn't done it yet, the chances of it happening are...slim.
I favorite a lot of tweets. Sometimes it's because someone said something nice and I was having a bad day, and I appreciated the kind words. Sometimes it's because it was a pretty funny joke I want to tell someone later. Sometimes it's because it's something I would like to remember for future reference. I have never favorited a tweet because I thought "Hot damn, I'd like to hit that." Assume that favorites mean nothing. It's clicking a button, it isn't interaction. There's a guy I follow that favorites every tweet that comes his way, because he's just being nice to people. It doesn't "mean" anything.
And by that I mean the person you know, the person that tweets all the time, is not a "real" person. That is a person who is crafting their tweets to be funny, or kind, or to deliver a message. Messages, humor and kindness are all great, but who they are when the turn the computer off? That's real. That's the girl you don't get to see. And she may have a boyfriend, she might have a husband, she might not be interested in a relationship for whatever reason she has, but if she's not public about it, it's because that's private information. Public face and private face are two very different things. You get to see exactly what she allows you to see, nothing more.
You point out that she's "internet famous," and you're a "regular guy." Guess what? She's a regular girl. She just happens to have more people paying attention to what she's saying at any given time, for whatever reason.
I can't speak for her, because I don't know her at all. And you really haven't given us much to go on here. But I know as far as I'm concerned, the biggest turnoff in the world is someone who points out my "internet fame," however small that might be. Because all that says to me is you're interested in what I do, not who I am.
Anyone can make it with anyone, if there's a connection there. But there has to be a connection - and a few favorited tweets aren't a connection. If the only reason you're tweeting at her is because you have this crush and expect some kind of response, and you haven't gotten any response, chances are you aren't going to get one.