Anything's possible, but, if one is to believe the accounts of both Gable and Monroe, the answer is no. Both on and off the set, they expressed genuine admiration, respect, and affection for one another, and Clark Gable in particular took a rather protective, paternal interest in Marilyn; the two of them were often seen between takes sitting off alone in private conversation and, in the instances where Marilyn did show up late, it was Gable who generally came to her defense, jokingly saying things like "why is it that sexy women are never on time?".
It is true that Marilyn Monroe was dealing with very difficult personal issues during the making of this film- including the break-up of her marriage to playwright Arthur Miller- and was often under the influence of drugs and alcohol during the production. She was often late to the set, and production was even halted for about a month so that Marilyn could be checked into a hospital for detox.
But the hot Nevada desert was a difficult film location for all concerned in many respects; most of the principal actors and many of the crew, not just Gable and Monroe, were often exhausted both during and immediately after the film's production. And Monroe wasn't the only star causing problems and production delays during shooting; Montgomery Clift was also battling drug and alcohol abuse during the production, often causing Gable to lose his patience (and his temper).
After Gable died, a reporter quoted a comment from Kay Gable, Clark Gable's wife, that she felt that the "eternal waiting" on the set of "The Misfits" had contributed to her husband's death, but Mrs. Gable didn't specifically mention Marilyn Monroe and, as stated earlier, shooting a film in the desert is almost always an arduous task at best and production delays in such conditions are generally the rule and not the exception, even when the principal actors are consistently sober and focused every day (which clearly Monroe and Clift were not). Further evidence that Kay Gable did not blame Marilyn for contributing to her husband's death can be found in the fact that, when Mrs. Gable held the christening for her son, John Clark Gable (who was born four months after Gable's death). she personally invited Marilyn to attend- and indeed Marilyn did.
In any event, when Marilyn Monroe did cause production delays, it was probably a more positive than negative thing for Gable, as his contract for "The Misfits" guaranteed him a staggering $48,000 a week in overtime pay, so the longer he was there, the more money he made.
Finally, to blame Gable's heart attack entirely on stress caused by Monroe is unfair, as Gable's lifelong history of crash dieting, hard drinking (up to two quarts of whiskey per day), and heavy smoking (three packs of cigarettes and a dozen cigars per day by some accounts) undoubtably played a part in his untimely demise from heart failure just days after filming was completed. In addition, as mentioned elsewhere in this FAQ, Gable was an outdoors type, a "man's man", and insisted on doing many of his own stunts during the production; this would have put a great physical strain on anyone, especially a 59 year old man who was not in peak physical condition at the time.