Yes, Notion is funded. It's backed by investors such as Index Ventures, Kleiner Perkins, and CRV. Notion has raised $13.9 million in venture capital. The company's most recent financing round was a $10 million Series A in April of 2016, led by Index Ventures and Kleiner Perkins. A further $3.9 million was secured in seed capital from CRV in February 2015.
Notion has also received numerous awards, including first place at TechCrunch Disrupt NY in 2015, and being named one of the top 100 startups in Y Combinator’s class of 2017.
Notion is quickly gaining traction and is already being used by thousands of individuals, companies, and students. Its features, ease of use, and affordability have attracted a number of high-profile users such as NASA, Google, and Facebook.
If you'd like more information about Notion's funding, you can read up on their blog (https://blog.notion.so/notion-is-now-fully-funded-1a927597a443). You could also check out their fundraiser page on Crunchbase (https://www.crunchbase.com/organization/solo-gym).