An Afrikaans structure
dat ek jou dit hoor sê het.
What will it be if dat is not there?
and what is its past tense and present tense form?

Question

An Afrikaans structure
dat ek jou dit hoor sê het. 
What will it be if dat is not there? 
and what is its past tense and present tense form?

Answer

I'm not sure what the context of the sentence is. So I won't be able to give you much information on it.

"Dat ek jou dit hoor sê het" I would say is past tense. 
If you want it to be in the present tense, it should read something like this: Ek hoor jou dit sê.

I hope I'm not misguiding you here!