The reason I keep asking about your type of gate release is that I I have had issues with AC releases before - read this for more info:
It depends on the code.
If it’s not well written then it may not be suitable for adapting for use with Blynk, which is why I said:
One thing we will need to know is whether the relay you’re using is active HIGH or LOW, and which GPIO pin you plan to connect it to.
Pete.