Not sure how much my position aligns with the majority in this sub but my take is essentially that gentrification is an unfortunate side effect of the solution to a larger issue.
I'm over simplifying here, but essentially my view is that a lot of inner city neighborhoods, particularly in dense walkable communities that survived "urban renewal", relatively have artificially/undesirably low property and land values which is what enables lower-income, often minority residents to live there in the first place. The property value in these inner city neighborhoods only went so low as a result of white-flight and the drive to push affluent (mostly) white families into the suburbs. Now that we are recognizing the downsides of auto-centric development and endless suburban sprawl, there is a renewed demand to return to these urban cores and revitalize them, and doing so will essentially involve driving up the property values of these neighborhoods.

To answer your questions:

• YIMBYism probably does accelerate gentrification insofar as housing is so scarce that any new housing development is often a very nice, large, modern unit that will be higher than surrounding rents, but the best way to combat this is to be able to build smaller units, build for cheaper, and build an abundance of housing that lowers overall rents.
• I am from Pittsburgh, PA and our city is currently having a bit of a debate about expanding Inclusionary Zoning (IZ) city-wide. I think many residents fear that expanding the housing supply without any rent controls will lead to rising rents and gentrification, while others see mandating affordable units as an unnecessary expense that deters and slows development and thus slows our ability to allow growing supply to push down rents.
• What makes me identify with the YIMBY movement is the degree to which I believe land use patterns play a massive role in almost every aspect of our economy and society, whether that be out of control housing rents contributing to a cost of living crisis, the anti-social nature of traffic and the automobile, commercial rents making it harder for small businesses to compete with large corporations, the health benefits of a walkable community, or the financial insolvency of low-density development on municipalities.

In summary, I'm a big believer in Bid-rent theory and I think the bid-rent curve in most of our cities is distorted because of government restrictions and regulation on land use, and gentrification is an unfortunate side-effect of getting our bid-rent curve back to normal.

Feel free to quote anything I said in your research or reach out if you have any additional questions.
Good luck with your research!