Earlier today Remedy confirmed that Quantum Break will include Brazilian Portuguese Localisation! The confirmation came through Twitter and just in time for the Brasil Game Show which the developers are attending over the weekend.
We are happy to confirm #QuantumBreak will have full Brasilian Portugese localization @XboxBR @NaxlaMina #brasilgameshow #XboxBGS @XboxP3— Remedy Entertainment (@remedygames) October 9, 2015
I know there were a lot of questions appearing in response to the announcement about if the game was going to be localised for a specific language. So far the only language localisation confirmed are English and Brazilian Portuguese, but more will be announced closer to April.
For a quick general idea about what languages might be included, we can look at Alan Wake. For Wake's launch on PC, sidetwo (our lovely community manager at the time who betrayed us for better people) posted a Q&A on Steam which included localisation. "It is localised to same languages as Alan Wake Xbox360 with full voiceover and text localisations for English, German, Italian, French, Spanish and Japanese. Text localisation (Subtitle support and menu translations) will be provided in Traditional Chinese, Korean, Polish and Russian."
As mentioned before, Remedy hasn't touched localisation just yet. It's possible that they're talking about Brazilian Portuguese now as this would be the first Remedy title to include it. If you can't find any information about the game being in a specific language, this isn't a problem, it's just hasn't been talked about in depth too much yet.