Here is an article that should give you a solid start in the topic. I'm sure in the intervening years other articles have been written, but it's a start.

And, of course, the essential historical context.

So, to work backwards a bit, Soviet historiography was more or less explicitly Slavist. Now, I'm not sure where it gets this tendency, but I have my suspicions - it was a fairly popular attitude prior to the Revolution, but Stalin or some Stalinist may have codified it.

Historically, historiography was less rigorous than it is today (and even now, historiographical narratives are being challenged daily!) and political/moral motivations abound. Just so happens that the orthodoxy of Russian history was rather separate from the West and rather more politicized since... well, honestly, forever.

Now, the arguments for Varangian origin are, basically, that the Rus are included in the Primary Chronicle and in Byzantine records as viking, that Rus names in those sources are pretty obviously Varangian, and that the name Rus may be Varangian in origin.

The arguments against are that the name Rus predates the Norse invasion of the region and refers to the southerly region of Kiev and not Novgorod, the lack of a distinct Rus tribe amongst Scandinavian sources, there isn't archaeological evidence to support large Varangian population, and that the Varangians present at the Byzantine court were just minions of the Slavic princes.

The short of the etymological questions is that it's a damned mess. While Rus may not trace back to any Scandinavian source we can attest, the supposed Syriac and Muslim Arab sources referenced a tribe called Rus are rather unlikely. The article's author specifically warns against delving into this shitheap at all.

As for archaeology, the other strong anti-Varangian claim, one need only look to England, where virtually nothing Norse survives, but yet the Norsemen were, without any doubt, there.

He goes on quite a bit longer at trying to solve this problem, but I took Imperial Russian history with an excellent historian by the name of Khodarkovsky. To paraphrase K.'s response to the argument, people who want it to be one way or the other are probably racist. There were Slavs there, who were conquered by, or otherwise integrated with, Varangians and eventually you just couldn't tell the difference. To paraphrase a man quite famous in Russian history, struggle erases national borders.

hi! FYI, there have been a few posts on this general subject; while they don't tackle your question head-on, you may find some of the discussion of interest

How did the ukrainian culture develop after the Kiever Rus? Why did people claim ( and still do ) that the ukrainian culture and ethnicity are made-up/fictional?

How did Belorussians and Ukrainians evolve as distinct national identities from Russia?

Was Kievan Rus' founded by Vikings?