The only hope for Manchester United is to win their match against Galatasaray, and if possible win Bayern Munich or draw them, but if they fail to win Galatasaray away from home, they need to put all their effort to win Bayern Munich which I know will be very hard for them unless they are lucky.
If Copenhangen can get a surprising win against Bayern, then it will be over for Both Galatasaray and Manchester Unite. But as it stand now, Galatasaray if they are able to win Manchester United will have hope of qualifying ahead of Copenhangen because winning Bayern will be hard for them.
It will only be a hope for them if they win but if they draw there's no hope winning is the only hope because if they do they will be having six points and Copenhagen may likely draw or loose against Bayern but I don't think they could win because bayern is in a very good form.
The results of the game against Copenhagen doesn't really matter to Bayern because they have qualified already so they could choose to win or loose against Copenhagen but if they eventually loose against Copenhagen then Manchester united wins, they will have to be differentiated by goal difference and Manchester united currently have good number of goals so it may most likely favour Manchester united but then these are all speculations, Bayern Munich is the only team who has gotten a guaranteed qualification in their group already.