Is there going to be a GTA 6

Seeing how they made so much money off the 5th one, most likely, yes.

I think they will make gta 6, but currently they are developing gta 5, so gta 5 would be available for ps4, xbox 1, and pc.

theirs a good chance there will b but not for a while

There will be a GTA 6, this is a hugely được ưa chuộng series and like Zelda and Mario, they will continue to make new games for it. I enjoy this series so much and hope they make the sixth one better than all the other games. I also heard that they may have us play as a cop instead of a criminal.
Here is proof:
link

There is a great chance that Rockstar Games will produce a GTA VI!