I think they are geared towards entirely different audiences and have very different use cases and design structures. When you ask if it could overtake Steemit, I'd need to know in what capacity you mean.
Can ONO have more active daily users? Sure.
Can ONO overtake Steemit in quality content? That's very subjective.
Can ONO overtake Steemit in market cap? That's entirely up to the subjective value of the market and you'd have to compare ONOT to STEEM. I think STEEM is a much more versatile token with infinitely more functionality and use cases than the ONOT burn for advertising model. It's like comparing apples to oranges and ultimately kind of irrelevant/flawed on the basis that they do very different things.
It's hard to know if I'm answering the actual question you are asking, but if you'd like to clarify, leave me a reply and I can potentially provide better insight.