The price is set at the margin and is a result of demand more than supply. Total Supply is known, demand is the unknown. Price goes up from more buyers then sellers not as a result of btc issuance. Although the halving does have a price shock effect due to half as much supply being sold at the margin by the miners each block. Miners are typically the largest sellers so them getting half as much BTC ever 10 min results in less selling pressure.