Yeah, besides both having giant humanoid robots Pacific Rim doesn't look like it's specifically borrowing anything from that series (and indeed, judging from the trailer these robots are being remotely piloted).
No, the pilots are actually inside the Jaegers' heads:
It's a mashup, Mecha vs. Kaiju. Guillermo del Toro playing with toys on a huge budget. Could be fun.
Actually giant mecha have been part of the daikaiju genre for decades now, going back as far as the alien robot Moguera in the 1957 The Mysterians
. The first battle between a living daikaiju and a giant mecha was probably in Godzilla vs. Mechagodzilla
in the '70s. The original Mechagodzilla was a robot built by evil aliens, but the second and third incarnations were both human-operated military robots for battling Godzilla -- the '90s version had pilots inside and the '00s version was remotely operated from a nearby jet. There was also the '90s version of MOGUERA in the abysmal Godzilla vs. SpaceGodzilla
, which was the successor to the piloted Mechagodzilla from the previous movie. It was combined from two separate vehicles, Sentai-style. There was also Mechani-Kong in King Kong Escapes
in the '60s, the Ultraman-like Jet Jaguar in the '70s, and the cyborg Mecha-King Ghidorah in the '90s.
So while there's been cross-pollination between the kaiju and mecha genres for decades, I think it's fair to say that Pacific Rim
is a straight-up kaiju homage.