Yes, it can be used as "according to", but this usage is mostly found in news reports, and it can only be used after the statement.
For example, you could not say
"So die Bundesagentur für Arbeit, nahm die Arbeitslosenquote um 0,2 Punkte auf 6,5 Prozent ab."
"So" essentialy means "like this", so literally it would be
"The unemployment rate declined by 0.2 to a value of 6.5%, (saying it) "like this" (/according to) the Federal Employment Agency."
If more citations follow, there can also be a "weiter" (continuing/further) added. As in
Die Zahlen des nächsten Monats werden bald vorliegen, so die Agentur weiter.
The values of next month will soon be available, "so" the agency "continues/further".
You wouldn't use it like this in a conversation, as it's a typical news report phrasing.
To say "according to" it's more common to use "laut" + Gentitv or Dativ (according to Duden, both is OK), which is used before the statement. As in
"Laut der Bundesagentur für Arbeit nahm die Arbeitslosenquote um 0,2 Punkte auf 6,5 Prozent ab."