I need to create an ETL system which will recive data from a user through survey/Form -> the data will be stored in a database/dataset -> calculations will be done -> the calculated data will be presented on a dashboard (Hopefully the survy and the dashboard will be on the same web page/portal).
Could i use for these porpuse Power app and power BI?
What are the basic architecture/connections i need?
Depending on the complexity of the form and the intended audience, you may want to consider using Microsoft Forms rather than PowerApps.
PowerApps can write the data directly to your dataset. IIRC with Forms you'll need a Flow to write the responses to your dataset.
I'm not a PowerBI expert but you may want to look at the Streaming data capabilities so that changes to your data source are reflected in your visuals in real time.