I was reading an article in New Yorker. I found the following sentence:
In his book “Vladimir Nabokov: The American Years,” the biographer Brian Boyd writes that, "as Nabokov ----."
Question #1: Would it be writes/wrote/has written?
Question: #2: Is the comma after that appropriate?
1 It is "writes," since that is what is written. Writes is used because it is referring to the text in a book. Even if the author Brian Boyd is dead, we would still use "writes," because the book still speaks, and it speaks in the present tense.
Hemingway (a famous author who is dead) writes in A Farewell to Arms "blah blah blah..."
2 We can't really tell if the comma is appropriate, since you didn't provide the complete sentence.
In this case, writes seems to be the most appropriate choice, even if wrote and have written are correct too, but give a stronger sense of past, as if the author does no longer have this opinion. As for the comma, it is perfectly correct and separates the quotation from the rest of the sentence.
The words "has written" are better to my ear than "have written" in the text in the question. In that context "have" suggests either more than one or it suggests a person; it works in the sense "they have ...". By contrast the word "has" suggests just one in phrases like "he has ..." or "she has ..." or "Brian has ...".
