The last few mainline games have all ended up in a similar place:
- Resident Evil 4 - 11.40 million
- Resident Evil 5 - 12.80 million
- Resident Evil 6 - 10.40 million
- Resident Evil 7: Biohazard - 10.20 million
And RE2 Remake will be joining them shortly at that level (RE3 Remake won't, but it's not mainline and it had a pretty mixed reception).
So 11+ million easily. Lifetime it's hard to say though, because it'll be ported to future gen consoles and will sell on PC for decades. All of those listed above still sell 0.5-1.5 million a year, for example, which is well over a decade since they released in some cases. Maybe 14 million final final final total?