what they shares

[CarloSsS]

Is it acceptable to use 3rd person form after "they" in contexts like this one?

Do you know Jamie? To see what they shares with friends, send them a friend request or message them.

I'd use "share", but then again "they" could be substituted with "he or she" and then "shares" would be OK.

 

[SoothingDave]

No, it's not OK. He (or she) shares fits here.

 

[5jj]

If you've used a name, there is no need for 'they'. We know that it's one person, and we know the gender.

 

[CarloSsS]

... ans we know the gender.

Jamie could be a girl's name too, couldn't it?

 

[5jj]

Jamie could be a girl's name too, couldn't it?

Yes. But if I don't know (of) a person called Jamie, then I am probably not going to use their name.

In that particular sentence, above, 'their' might be appropriate. In the original, the speaker would use 'his' or 'her' as appropriate.