Rozdíl je v tom ten, že I WILL GOING TO vubec neexistuje.

"I am going to the cinema tonight" means that your plan to go to the cinema is already in process. For example you have already paid for the tickets so you know that you ARE going.
"I will be going to the cinema tonight." means that you have an intention (záměr) to go to the cinema but may be you haven't done anything for it yet. It is the same if a young child says - "I am going to be a policeman when I grow up." It is his intention but he hasn't started the process yet. Understand?

Hello,

Although the second sentence contains a small mistake, what you're probably asking about is the difference between WILL/GOING TO, i.e. the difference between "I am GOING TO the cinema tonight" and "I WILL go to the cinema tonight" 
It all depends on WHEN THE DECISION WAS MADE. 

If the decision to go to the cinema was made BEFORE the moment of speaking about possibilities for the evening, then it is a plan, therefore one would say:
"I am going to the cinema tonight." 

However, if the decision to go to the cinema is made during the moment of speaking about possibilities for the evening, it is not a plan, and so one would say:
"[Oh, I don't know, maybe] I'll go to the cinema tonight."

Rozdíl by měl být mezi větami :
Iam going to the cinema tonight x I will go to the cinema tonight x I will be going to the cinema tonight.

I am going - půjdu do kina, plánuji, mám vše zařízené, je tam jasný záměr
I will go -půjdu do kina, jistota, plány jsou jasné, je to věta oznamovací.
I will be going - mám v plánu jít do kina, musím zařídit další věci

I don't think so. The other sentence is complete nonsense. You forgot verb BE there. What is “BE”? so why would you describe to somebody your walk to the cinema? Why would you tell somebody what you certainly will BE doing …walking on foot there or by bus eating cornflakes? What does “will” mean? “will” is your decision that you just made… if so, then you just decided to BE … to be what… going…"I will be helping the cinema overcome their crisis"... what about this sentence compared to yours "I will be going to the cinema" or this one "I will be walking to the cinema again and spending all my energy to climb the hill that it is located on"... It is even more complicated ...I will be working, walking, singing, reading.... what´s the cinema got to do with it?

V první řadě se zaměřte na rozdíl mezi budoucími časy. Will poukazuje na obecnou budoucnost, pravděpodobné plány, nemá zcela dané ohraničení dokončení děje v budoucím čase. Zatímco going to je forma vyjádření plánované budoucí akce, něco co se odehraje velmi brzy. Pro vaši větu je správně. I am going to the cinema tonight. Je to plán na večer. I will go to the cinema / obecný předpoklad, že půjdete do kina. To co jste napsal s will going to - je gramaticky špatně. Docela hezky to také shrnuje tento článek: https://www.helpforenglish.cz/article/2007052802-budouci-cas Hodně štestí. “Only practice makes master.”