The German international has struggled badly with injury this season and has made just one Bundesliga appearance, back in August.
However that has not stopped him being linked with a host of clubs, including Manchester United.
According to Bild, Gundogan has offers on the table from both the Red Devils and Real Madrid; Manchester United are said to have offered €30 million to take him on in the summer while the Spanish giants want to use striker Karim Benzema as part of the deal.
The 23-year-old, who has 18 months left to run on his contract, is quoted as saying by Bild: "I will soon make a decision [about my future] that will be well considered. It’s still really open."
Whether Manchester United will be able to lure Gundogan to Old Trafford remains to be seen given Real Madrid's interest.
Under David Moyes, the reigning Premier League champions face a fight to qualify for the Champions League this season - however the promise of more regular game time at Old Trafford may sway him away from Spain.
Moyes and Manchester United were linked with a host of midfielders in the summer, before landing Marouane Fellaini from Everton for £27.5 million on deadline day.
Should Gundogan decide that his future lies away from Germany it would be another blow for Dortmund, after they finally lost striker Robert Lewandowski to rivals Bayern Munich earlier this month.