Show solidarity with them. First things first is don't give that business any money until the workers win.
Have they talked to any union organizers, or are they going it wildcat? If they don't have real support behind them to help pay bills etc, the strike will fold quickly and likely be unsuccessful - the boss just has to outlast them. Strike funds are crucial for this reason. If the workers don't have a way to meet their needs, they'll lose.
Local social media and news outlets are good places to broadcast the strike. Talk to people at similar businesses and see if they can join the strike.
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