Nominal clause

Fandorin"The temptation to surrender is as stronger as you are closely to win."
Is underlined a Nominal Clause in a function of the Subject?

I don't think I'd call it a clause, but it's nominal, and it is the subject. The sentence itself is ungrammatical, however.

stronger means more strong.
as strong means equally

" The temptation to surrender gets more stronger as you get close to winning"
Can I say that way?

That's better.

But you have stronger, which means more strong. So more stronger mean

Some people would call it an infinitival clause, but it is better to refer to it as a phrase since it doesn't contain a verb (at least it doesn't contain a verb that is functioning as a verb).
A nominal clause begins with the subordinators that, if, whether, or any of the wh question words.

Examples of nominal clauses are: 

That you will surrender is lik

CalifJimThat's better.

But you have stronger,

Thank you, Richard_s. "The temptation to surrender" - Is "to surrender" an attribute to "the temptation"?

Well, mostly 'attribute' is used for adjectival or descriptive words, phrase, and clauses which come before the noun or clause being described.  Those that come after are called predicative.  In this case the infinitive is acting in a descriptive manner; it is very similar in use to a relative clause; however, the technical term is 'complement'.

Fandorin"When you’re ready to quit, you’re closer than you think. "

I think you may have the wrong interpretation of this. Those last three words than you think are very important.

It means,
You've worked very hard to build your business, but you've had setbacks. You keep struggling, but success still seems far away. You get so discoura

Yes, I see I got it wrong. The last idiomatic expression is very useful. Thank, CJ.

Thank you, Richard_s.