Are you using your transports? Best thing you could possibly do is just stay way back and pick him off with ranged. If you're focus is on Suits then JSJ further away while pelting him with shots. Really, anything that keeps you out of CC is going to be a boon for you. Really its gonna come down to what units you and he are using.
Does he use Lootas or Bikes? Things like that will be a priority for you as they threaten your range advantage.
Sorry, that's about all I can do... I don't know Tau too well but I hope it helps a bit. Maybe someone in the Tau Army section could be of more assistance.
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