Does sivir mercenary get +2 if you recycle 2 runes

No — recycling alone doesn't count. Sivir, Mercenary cares about power you've spent, not power you've generated.

Recycling two runes adds two Power to your Rune Pool (Rule 164.2.b), but that's just "floating" it — nothing has been paid. Her text is "If you've spent at least [A][A] this turn, I have +2 [M] and [Ganking]," and floating power in your pool isn't spending it. The moment you actually pay that power for a cost (a card's Power cost, an ability, etc.), she immediately gets +2 Might and Ganking for the turn — FAQ #7571 confirms the bonus turns on as soon as the cost is paid, before the spell/ability resolves.

Also note you can't be forced to spend floating power: the Vendetta "Payment Optional" change (Rule 444.2) means having 2 Power in your pool doesn't compel you to use it, so no accidental trigger.