Will the payout for mining will always be the same? Will the payout for mining always be 0.00000064 BTC?
Because that is what i just got.
No. The payout is determined by the block reward divided by the difficulty. The block reward halves every 210,000 blocks and the difficulty changes based on the total amount of mining.

As I write this, the block reward is 25 BTC and the difficulty is 37,392,766. Dividing gives .0000000668, which would be the pay per share at this moment for a pool that charged no fees and kept all transaction fees.