Vote is underway, results should be out in the next 30 minutes.
Steinmeier likely won't get the full 1106 votes, but somewhere between 920 and 1100 - i.e. only a 80% majority; i'd personally expect around 1050. The Kurnaz/Guantanamo affair in particular isn't forgotten and will take votes from him not just among the Greens, but also in other parties of his coalition - there are even a couple CDU delegates citing Kurnaz for their decision not to vote for Steinmeier.
The Federal Assembly was opened at 12:20 by parliamentary president Norbert Lammert (CDU) who gave a speech warning Trump against isolation and protectionism ("whoever calls for that shouldn't be surprised if others do it alike") and explicitly calling for a "strong Europe". He got standing ovations for that speech from pretty much everyone except the 35 present AfD delegates.