The article links to a great resource, the shadowstats.com Inflation Calculator, which provides pricing information based on official and unofficial inflation data, a so-called price deflator.
The input on the official price of gold is slightly variant (but the correct messaging is spot on), as the author inputs an official price of $20.79 in May 1913 (the same year the Fed was created, not so coincidentally). The actual official price of gold back then was $20.67, while the average price of gold based on the London Fix was $20.64, according to kitco.com <click here>.
The input on the official price of silver also differs, according to whether one uses the official price or average price for 1913. The unofficial price of silver based on the London fix was $0.58, according to kitco.com <click here>. The author uses an official price of $1.29, which may be accurate (there is very little data on the "official" price of silver, which presumably was set by the US Treasury).
Bottom-line: the article points to the Inflation Calculator which indicates how much the USDollar has been debased by perpetual currency and credit creation from the Fed and US Treasury, as reflected in the prices of gold and silver.
Interestingly enough, the Minnesota Fed provides a similar calculator, named "What's a Dollar Worth?" on their website, based on official CPI data <click here>.