How to load gzipped json data from a copy
You are missing json_option (http://docs.aws.amazon.com/redshift/latest/dg/r_COPY.html). Try setting it 'auto'. See corrected example below:
COPY tmp_data FROM 's3://mybucket/copy/batch_insert_data_1417072335118.json' credentials 'aws_access_key_id=XXXXXXXXXXXXXXX;aws_secret_access_key=YyYYYyyYYYYYyyYYYYyyYYYYY' json 'AUTO' gzip ACCEPTINVCHARS ' ' TRUNCATECOLUMNS TRIMBLANKS;