Is it correct the correspondence between probably/surely and should?

Is it correct the correspondence between probably/for sure and should?

I mean, if the use of should is correct, besides to have the same meaning in phrases like:

He should be ok ←→ probably he is ok ←→ he is ok, for sure

Context added

When, for instance, I have no news from him for a long time and I wonder, or somebody ask me for him, then I answer with the previous phrases.

Solution 1:

They are different.

The gunshot missed him. He should be okay except perhaps for shock.

"should" indicates that the circumstances suggest he's okay.

probably he is ok

This is more tentative. It means we don't know. It could be that he is very capable and lucky so we ascribe a high probability to his being okay.

he is ok, for sure

He is definitely okay. Of course this could be used as a reassurance to someone where there is doubt in the mind of the speaker but they wish not to upset the other party.

EDIT 1 in light of new context.

I wouldn't use any of those. Here are my suggestions:

Somebody: How's John these days?

You: As far as I know he's okay. I haven't heard from him for a long time.

This indicates that you don't know and may not be very interested in John's fate.

or

Somebody: How's John these days?

You: I expect he's okay. I haven't heard from him for a long time.

This indicates that you think he is probably okay because "no news is good news"

https://dictionary.cambridge.org/dictionary/english/no-news-is-good-news

EDIT 2 in response to comment by @Andrés Chandía

For me, the phrase, "he should be okay" is more likely to be used as a prediction, e.g.

Somebody: Look, John is about to go into that cave! Will he be safe? There might be a bear in there.

You: He should be okay. He is an expert cave explorer and will certainly be looking out for bears.