Why in this case I have to use to hear and in other cases like these:
I look forward to hearing from you soon. :tick: Put a period at the end of a sentence.
I hope to hearing from you soon. :cross:
I hope to hear from you soon. :tick:
have I to use to hearing? Because is it intended in future tense? No, both correct sentences refer to the future. The difference is because of the grammar difference between the phrasal verb "look forward" and the verb "hope".
I look forward to verbing.
I hope to verb. (no "ing')