Is it true that eating after 8 PM makes you put on kilograms (pounds)?
It is possible. You need more calories when you're active and fewer when you're sedentary. So, if you're eating the bulk of your calories while you're sitting in front of the TV, you may indeed store more of them as fat.
However, what matters most when it comes to losing weight is how many total calories you take in and burn off throughout the day, not just within a limited time frame. If swearing off snacks after 8:00 helps you reduce your overall calorie intake, go for it, but don't forget to keep track of the whole day's tally as well.