The extra reinforcements and settlers may have helped in consolidating the gains the Crusaders had already made, but without a safer and more efficient line of supply and travel, the Christians of Outremer would always be outnumbered significantly. An earlier establishment of a Catholic kingdom in Cyprus would help significantly, as would the seizing of islands like Malta and Crete that could serve as ports of call for Latin fleets heading east who could also all more extensively raid Egypt, Libya, Tripolitania, and Cyrenaica.
Most importantly, these Christian states must establish a friendly relationship with some of the Muslim kingdoms around them, if at least to play off the competing powers against one another. If trade can be established and allowed to flourish, the Christian states could have more long-term viability, but will always be susceptible to the threat of a united Muslim coalition, which could still easily sweep them aside if they could avoid their own infighting.
Malta was already in latin hands by 1101. Attacking Cyprus and Crete in this era is risking the Crusader States very existence.
The Crusaders could, as you said, use the extra settlers. More manpower and loyal population. It may not necessarily save the Crusaders but it may help if the Second Crusade Helps, means less loses. Edessa especially could use more loyal forces. Ideally is of course no Second Crusade.
For long term survival these settlers are not enough though. Some other requirements are:
- divided Islamic Middle East (Levant and Anatolia at least)
- the Romans not subjugating the Turks in the interior but not losing too much either (no 4th crusade, will not happen anyway
- Georgia remains stronger
- Non-Catholics slowly absorbed by the Latin Christians. Then the attempt conversion of various groups (starting with the Ismailites, Alawites, Druzes and later a daring attempts on the Sunnis). Conversion attempts usually alienates the populace but for long term rule it is ideal. Going from the weakest groups until there are two. With a bit of luck of course you get a new mixture of Latin, Levantine and other cultures as one new culture in the Holy Land. And that is what the settlers are good for.
Of course this also needs a lot of luck...