Does what someone wears to an interview matter?

HELP! I put in for a job on a whim and actually got an interview. It pays almost $12,000 a year more then I am getting now and I am terrified! I haven’t had a job interview in over 10 years! Does what someone wears to an interview influence your decision in any way? I am not talkin’ belly button rings and jeans here. Casual slacks? Dress? Suit? Dressy…non dressy? It is in I.T. so I just don’t know whether this is a big consideration among those hiring nowadays. Any opinions would be appreciated!! But BE NICE…I am old and get my feelings hurt easily! LOL!!