I took this data across data that we know for BTS:
BTS currently have around 43.8B Streams across Spotify, YT, Melon (these 3 are numbers from today) and Apple Music (AM data is from late 2018).
Spotify at --> 15.13B
AM at --> 1B (data from late 2018)
Melon at --> 9.56B
Youtube at --> 18.15B
Spotify is taken straight from Spotify counter that is also easily tracked by a BTS chart account called BTS Graphs with their website:
Youtube is taken from kworb (atm this is the only source that provides a total number properly, but take into account that this isn't just MVs but includes dance practices as well, but it does exclude all bangtan bombs and other stuff).
Melon streams are taken from guyso.me --> https://xn--o39an51b2re.com/melon/artiststream/672375
And finally we know that BTS surpassed at least 1B Apple Music streams as it was announced in 2018. Reminder that this was before a bunch of BTSs recent music including 2 of their biggest streaming songs (BWL and Dynamite).