Actually no.
RDR has sold 13 million copies, quite a success for the second game in the Red Dead series.
GTA has always been on PC, Red Dead has never been on PC.
We don't know when RDR2 will release for PC nor do we know if Rockstar ever releases it for PC.
Chances of it releasing are as good as it never getting released.
Actually RDR1 kind of was a different situation. IIRC one of Rockstar’s given reasons for not porting the first game to PC was because the engine was a gigantic mess coding-wise, porting it at the time would have required a tremendous amount of resources as that would require sorting everything out with thousands of different hardware configurations in mind VS the grand total of
two consoles they built the engine around. I doubt they would make the same mistake twice, at this point it’s either that they don’t want to start development on a PC port of RDR2 just yet and would rather gouge interest over the coming months, or they don’t intend on releasing it on there period for business-related reasons. Seems unlikely since GTAV PC has been selling pretty well, though.