You need to simplify the core clause with which you have a problem and try to change it from the passive voice to the active voice as it is easier to understand.
whose publication has been viewed as marking the beginning of the
can be changed to
People have viewed (considered/regarded/understood/looked upon/thought of, etc)
the publication as marking the beginning of the Harlem Renaissance.
We view a lot of things as as things that have a different capacity, role, character, condition, etc. That's why "as" was used as a preposition to represent things that are viewed/understood/considered/regarded/looked upon/thought of in different capacity, role, character, condition, etc.
"marking" in the sentence is not something that leads a present participial pharase. It is a gerund that is used as an object of a preposition, "as". In the setnence, you can change "marking" into "something that marked the beginning of the Harlem Renaissance".
You have to change a verb into a gerund to use as an object of a preposition.