Gangjee's one-under 71 took his final aggregate to eight-under 280 as the diminutive pro joined three others in the 10th place.
Fellow Kolkatan SSP Chowrasia (283) signed off with two-under 70 to finish tied 19th, three shots ahead of Atwal.
Among others, Kapurthala pro Gaganjeet Bhullar (287) turned in two-over 74 to be tied 39th.
Digvijay Singh (291) stood tied 60th after carding an even-par 72 while C Muniyappa (293) came tied 70th.
Korean teen sensation Noh Seung-yul secured a dramatic one-stroke victory over K J Choi after pulling off an audacious final-hole birdie.
The 18-year-old Noh produced the unlikeliest of birdies at the par five 634-yard 18th hole to close out the USD two million tournament with a final round four-under 68 and a 14-under 274 winning aggregate.
Gangjee had a good start to his final round as he birdied the first hole. He was two-under after six holes but bogeys on the seventh, eighth and 10th left him one-over before he made amends with birdies on the 11th and 14th.
The 15th hole, however, cost him his third double bogey of the week and Gangjee needed to birdie the last two holes to salvage his card.