So is today (Monday 1 July) a bank holiday in Brazil?

I’ve repeatedly heard it being said in the news that the Brazilian government wanted to declare an extra holiday today to celebrate the World Cup victory. Did they do it?

The Predsident had declared a holiday today, exactly as you put it, to celebrate their Victory in the Cup.
Must be nice. Although even if he hadn’t, I doubt many Brazilians would have showed up today anyway.