Odell Beckham should Jr be worried about this curse. This is because once a person knows about a curse they get wrapped up in worrying about it. This then affects their performance. Beckham Jr. can still keep it cool, though, and not let it affect him. It's all in how each person reacts mentally.
I know there have been a string of teams that have had bad luck after being on the Madden games covers, but this does not mean that curses are real. Teams should ignore this kind of legendary nonsense and just do their best each season. When the season is done, they need to own their performances - good or less fortunate.
I think "Madden Curse" is a stupid superstition and Odell Beckham Jr should not be worried about it. I think if he worries, his focus might not be on the game as it should be and that might be actually the cause for an injury. So it might be that "Madden Curse" is a self-fulfilling prophecy.
Over the years, there have been a surprising amount of players who graced the Madden cover only to find themselves injured or effected by poor play the following season. This is all a coincidence. Odell Beckham Jr should only worry about working hard to develop his skills and not let his success get to him.