What does " 'Nation " stand for in this context?

Solution 1:

How about this:

Damnation [...] 3. In profane use: [...] b. as adj. or adv. = 'Damned'.

Their first example is from 1757:

"The wit with metaphors makes bold, And tells you he's damnation cold."

There are two more examples: Damn'd old puns over damnation hot tea in Cambridge (1772), and a damned Frenchman with his damnation horse (1843).

(Source: OED)

PS: In these three examples, damnation clearly was chosen instead of damn for somewhat technical reasons: In the first so that the line scans, and in the other two for variety. In Dickens' case I can see no such reason.

At first I found oerkelens' hypothesis convincing: avoiding censorship through creative abbreviation of a less commonly used variant. But the same chapter also has this: "So, then One more pull and you're at the top and be damned to you [...]". Incidentally, we can see another instance of unusual (to us) capitalisation here - again on a word that's likely to be emphasised.

Solution 2:

The apostrophe is present because 'Nation is a short form of damnation (Dictonary.com), used in the sense of

interjection 5. (used in exclamatory phrases to express anger, disappointment, etc.)

In your example sentence it is used as an intensifier, to mean but can’t make so absolutely, certainly sure of that.

Solution 3:

The apostrophe does not seem to be a mistake. Every single hit that google returns has the apostrophe.

However, the capital N, although in (almost) every result from Dickens, does not seem to be necessary. There are precious little other occurrences of this phrase, but this New-Zealand paper from 29 June 1872 seems to ascertain that the expression fits in a Suffolk dialect:

Poaching v. Preaching.
— Rector : “Good Morning Mr. Catchpole ! I'm Sorry that I See you now so seldom at our Service !”
— Gamekeeper (Suffolk) : “Well, Sir, all I can Shay is, if the N'ghbours knowed as I were rig lar at the Chu'ch, you'd be 'nation sure to Lewse pretty nigh Half yar Congregation !”

(I tried to copy the original text as faithfully as possible, bold mine).

As to the meaning, 'nation just seems to mean very, as in you can be very sure, although I cannot find many instances of it being used...

As others suggest, it may well be an alternative shortening of damnation. Etymonline shows that damnation was used as imprecation (spoken curse) from the 16th century.

For damn, the same source mentions that the explitive is from the 14th century.

Based on that, it seems the verb damn lead to the now still common expletive, but that at least for some time, the form (dam)nation was used instead, or next to it, similar in meaning, which, in print, may be explained by this (same source):

Damn and its derivatives generally were avoided in print from 18c. to c.1930s

So if Dickens wanted to avoid damn, chances were, 'Nation would be well-understood and serve the same purpose. :)