Correct, Tomb Raider reboot failed to meet sales target in the first few months, but later vastly surpassed 'em. Usually sequels (no matter if it's a reboot or not) are very front loaded but since they changed Tomb Raider formula so much, it gained a lot of new fans over longer period of time. Tomb Raider started with a bang in 1996, but then each sequel sold worse untill 6th generation of console entries. Sales hit bit above 2 million (less for Anniversary) but since development budgets went up the same time, it was situation that Eidos just couldnt deal with.
So far reboot has sold over 8.5 million units.
http://www.pcgamer.com/tomb-raider-reboot-has-sold-85-million-copies/
Massive increase and well deserved success story. Hopefully this new game manages to do the same, despire Microsoft deal and late release for PC and PS4.