Socialblade has a section for predicting how many subscribers a channel will gain over time.
Here is a random tech channel I follow. They had 40,900 subscribers on January 24th, 2021. Socialblade predicts that four months later, they will have 52,883 subscribers.
Four Months Later Result
Wow! I’m amazed at how close the number was — prediction: 52,883, actual result: 52,200!
Conclusion
I’m quite impressed with SocialBlade’s accuracy and will continue to update this article with prediction results. Interestingly, the predictions on Socialblade have not been updated/regenerated. It seems they do the calculation of the prediction only once.