Use ( For )
Because that sentence below, was used (is) in the sentence. What is the goal ?

How is that going forPaul: iTalki is a english class website.

John: How is that going for. What are they teaching you?Paulo: I'm listening FORVO right now

John: How is that going for. What are they teaching you?

Paul: iTalki is a english class website.Conversation:

Paul said: I'm listening FORVO right now
John said: How is that going for. What are they teaching you?
Paul said: iTalki is a english class website.

Question

Use ( For )
Because that sentence below, was used (is) in the sentence. What is the goal ?

How is that going forPaul: iTalki is a english class website.

John: How is that going for. What are they teaching you?Paulo: I'm listening FORVO right now

John: How is that going for. What are they teaching you?

Paul: iTalki is a english class website.Conversation:

Paul said: I'm listening FORVO right now 
John said: How is that going for. What are they teaching you? 
Paul said: iTalki is a english class website.

Answer

I've thought about it and I can't think of any context in which this phrase would make sense.  If it is part of a bigger text, I recommend you post it all so we can have a look at the context.  It may however just be wrong.

Answer

People can say
How is it going for you?
How was it for you?

Answer

'How is that going for' means nothing.

Do you mean 'How is it going?'    =  'Como vai?"

Answer

Hi Gilliard:

The sentence attributed to "John" is incomplete. Here is the common question.

"How is that going for you?"        It means the same  as  
"How---Is--That---Working---For---You"  or,   "Does that work for you?"

Similarly,  I might ask you,  if I spoke that way;  "How is the Italki Website going for you?"

It means;  "Does the Italki Website help you."

Answer

I add new information in my question.