Is there SIA staking?
No.
Since SC is Proof of Stake, would I be staking if I leave my SC coins on my bittrex wallet?
If so, what is the stake recompense lets say you were holding 1 million SC? and for how long would I have to hold it for it to "mature"
Where have you read Siacoin is PoS? It is not, Sia is mined by Proof of Work (blake2b algorithm). So no reward for staking. If you need more info:
https://siawiki.tech/about/pow_vs_poshi freinds some one help me to understand what meens the proof of burn in the eaod map of sia.
it can decrease the circulated supply or what
After a future update, hosts will have to burn a small fraction of their profits to demonstrate they are legit hosts (and so avoiding Sybil attacks). By burning them they are sent to a void address and so they can't be used again, reducing the circulating supply. With the current network size, the amount of burnt coins will be very small, but if the network of hosts becomes huge, the amount of coins burnt will be bigger than the the mining block reward (it will reach the minimal 30.000 coins of reward per block in 2020). If this happens the coin could become deflationary.
I hope your hard work from last months and years(?) paid out now. Good job.