Joe Duplantier plays through an EVH III EL34 amp head and 4x12 accompanying cabinet. You can also get close to their sound with a Peavey 5150. Lots of mid and not much use of distortion. Gojira is well-known for not using that many pedals like overdrives or compressors. Just a noise suppressor and for some tracks whammy/delay.
They’re the kind of band who let their amps do the work mostly. Combined with exceptional picking technique and you have the Gojira sound.
Or… capture the plugin.