Did you read your link;
https://natowatch.org/newsbriefs/2018/how-gorbachev-was-misled-over-assurances-against-nato-expansion
It states;
"None of the assurances of non-expansion were included in any treaty documents, as NATO makes clear in its official explanation on its website: “NATO allies take decisions by consensus and these are recorded. There is no record of any such decision having been taken by NATO. Personal assurances, from NATO leaders, cannot replace alliance consensus and do not constitute a formal NATO agreement”.
All the other comments mentioned are claimed to be quotes from personnel but none with linked sources Whether they support or do not support the argument.
Here are some comments with a different view from the same link;
""Former US ambassador to Moscow Michael McFaul labelled the idea of a reneged promise a “myth” in an interview in 2016. Other experts have labelled Russian grievances as a case of “false memory syndrome”."