No, the Steelers are not fining players who kneel during the national anthem, as claimed in a satirical article, Sports, Pittsburgh
NFL teams huddling up to devise plans for social change
Fact Check: Mike Tomlin Suspends 2 Steelers Players for Anthem Kneeling?
Tomlin: Steelers will support players if they opt to kneel - The San Diego Union-Tribune
Notes from Coach: What Bill Belichick said after Patriots' Week 3 win vs. Steelers
In showings of protest and solidarity, NFL teams respond to Trump's criticisms - The Washington Post
Taking the knee: These are the NFL players protesting today
See Detroit Lions Anthem Singer Take Knee During Performance – Rolling Stone
Anthem protests began with a few NFL players. Trump's tweets engulfed all of them. - The Washington Post