Columbia Pictures chief David Puttnam says he isn't worried about losing authority or autonomy in a recently announced merger of his company with Tri-Star Pictures Inc. "It's fair to say I could be caught in the fallout," Puttnam told the Los Angeles Daily News, but added that he got "a massive vote of confidence" from the management of Coca-Cola Co., owner of both studios. Puttnam said he met with Coca-Cola chairman Roberto Goizueta and president Donald Keough and was assured that the two studios "will continue to run as separate entities and that . . . from the point of view of Coca-Cola Co., it's business as usual." Puttnam expects minor cuts in support staff in areas where Tri-Star and Columbia overlap.