The biggest issue with juices from plants that have lots of sugar is the concentration of that sugar. An eight ounce glass of orange juice has about 112 calories and 26 grams of carbs. About the same as 2.25 oranges. But the difference is that you can gulp down the oj really fast.
So, if you replace soda with fruit juice, you will be decreasing the number of carbs/sugars you get because sugared soda has tons more than oj. But you will still be hitting your system with substantial amounts of sugar throughout the day.
OJ is better than soda. Water is better than OJ.
A 12 oz glass of cold water with about a tablespoon of unfiltered ACV and three drops of stevia tastes awesome - but that's off-topic.
"Right is right, even if no one is doing it; wrong is wrong, even if everyone is doing it." - St. Augustine