...and probably 10s/100s of internal links where each of those pages have external links.

Did you research the ranked page?

Yes I know that mainly ranking reason is site authority but if you have ever been touched same competitor can you share your experience?

It's a little unclear as to what you mean by "your main competitor is Walmart". If you want to inform like paulgl implies, than sure, you might be able to outrank Walmart. If you want to sell, and you think you can outsell Walmart, think again. You'll need a different strategy.

Think Amazon. You can't outsell Amazon. But you can partner with them, use their brand and authority, and sell using and through them.

My experience is that you can partner in some way with large retailers and earn. Partnering can take many forms: affiliate sales, adsense revenues, contextual ads, etc, etc. I have never had any real or lasting success competing "against" them.

Good luck!

Go for it. Don't be afraid to create and rank a site just because your main competitor is a big authority site. With the right on page optimization and backlinks, any site can be outranked. It will require time, but it can be done.

thanks for answers
I am only immer I amn't selling my product. I want to try one product review site witch have about 60K search, I will use affiliate or adsense in future. But first I need ranking.