Short answer: Yes. Eligible marketplace enrollees can get both; the premium tax credit lowers the monthly premium and cost-sharing reductions lower deductibles and copays, but the cost-sharing help applies only to Silver plans.
The two ACA subsidies stack for those who qualify. Premium tax credits reduce the monthly premium across metal tiers, while cost-sharing reductions (CSRs) lower deductibles, copays, and the out-of-pocket maximum. The catch is that CSRs are available only on Silver-level marketplace plans and only to lower-income enrollees, so to capture both you generally need to choose Silver.