Modern day historians very rarely cite to Gibbon in any academic publishing. Most often you'll see a quote or comparison made to The Decline and Fall as some sort of emphasis or highlight, but not for his scholarly opinions or conclusions. Not because he's necessarily wrong, but in the two and a half centuries since he published, a lot of work has been done which contains significantly greater nuance and understanding. There are also articles and monographs that deal with individual topics in greater detail. Also, a small amount of new ancient evidence has been published which Gibbon could not have had access to. And as the FAQ says, his conclusions on why the Empire fell were clouded by the time he lived in.

There's lots to be said about Gibbon, and while you're waiting you can check out this section of the FAQ.