Soo, let's see...
6 LIs, set sexualities
Just as I fragging expected! I should try working at weather forecast station, I'd probably do a better job than them
Now, let's see...
Cullen is bi. Even if he was straight in DA:O, he was probably written by Hepler and Gaider for DA:I and it is hard for me to see them making Cullen straight
Cassandra is either straight or bi
As for possible LIs:
Vivienne, as I said, very possible, very gay or very bi. Very sure. Very Orlais and very Circle
Iron Bull - anything. Since even if he's a tal-vashoth, I think some of qunari ideals still stuck with him. So gender probably doesn't matter to him. And sex
Sera - if true, then bi, as usual. Though I wouldn't be surprised if they decided to do something unusual and she turns out as straight or gay only
Solas - ehh, too little information
Cole - nope
Scribbles - also too little information, but I think if Vivienne is a LI, then Scribbles will be either gay or bi, depending on Vivienne's sexuality. Maybe straight if Sera is gay and Cassandra is bi
Grey Warden - straight, likely? I have no idea
Dorian - gay or bi, likely
Varric - nope