The Great Gatsby. What do this QUOTE means?

It means that the fellow in question (Gatsby) is like David Belasco, a theater producer and playwright who is known for his realistic sets.

So, he compares Gatsby to David Belasco.

Explanation:

In the Great Gatsby, a dude who was at one of Gatsby's many parties who was expecting Gatsby's books to be fake just like everything else about Gatsby is fake. But the reverse was the case - the books turned out to be real. But Gatsby has never read them. At this point, the guy called Gatsby, "...a regular Belasco". Actually comparing Gatsby to David Belasco, a stage/theater producer and playwright.

David Belasco is known to have pioneered many innovative forms of stage lighting and special effects which he used to create realism and naturalism.

wordsworth tends to see nature as 'out there'; a presence which surrounds humans, and contributes to human life, but is different from humans. if you look at a typical wordsworth poem (there was a boy, ye knew him well ye rocks) - wordsworth talks about nature as something that needs to be learned about and understood, nature is different from us.  

if you look at a byron poem (the isles of greece is a good one) - byron looks at nature mainly for what it already means to man. wordsworth will look at a landscape and see the mountains, trees, valleys, and rivers as almost spiritual presences - wordsworth wants to get to know nature.  

byron will look at the same landscape and he will want to know who lives there, what are the villages? are there any farms or mines, is there some history?  

wordsworth looks at nature for what it is; byron is forever asking what it means.  

wordsworth thinks that humans are part of nature; byron thinks that nature is part of being human