"Were these Galileans more sinful ... way? No, I tell you" or "Does this prove that these Galileans were more sinful ... way? No, I tell you." Jesus uses this question to challenge the understanding of the people. Alternate translation: "You think that these Galileans were more sinful ... way, but they were not" or "Do not think that these Galileans were more sinful ... way" (See: [[rc://en/ta/man/translate/figs-rquestion]])
Here "I tell you" emphasizes "no." Alternate translation: "They certainly were not more sinful" or "You are wrong to think that their suffering proves that they were more sinful"