Scottish Government does now have some powers over Income Tax but they are only allowed to vary the basic rate up or down across the board - they cannot alter tax bands or personal allowances. As a progressive Government they will not do that because an increase would hit the less well off hardest and a decrease would mainly benefit the already well off. Any extra tax raised in Scotland would be deducted from the total due under the Barnett formula, leaving Scottish Tax payers paying more tax than their counterparts in the rest of the UK while the Scottish Government's budget would remain the same.
Power over Income Tax was one of the promises made by the UK government before the 2014 referendum to persuade Scots to vote NO to independence. The UK government now claim to have fulfilled that pledge but have set the rules in such a way that no sensible Scottish Government would ever enact them.
On the subject of the tax take from Scotland it is worth noting that if a person living in Scotland works as say- the Scottish Area Manager for Boots, B&Q or Tesco - then their Income Tax will currently be recorded as paid in England where their company HQ is situated. Similarly, VAT paid on goods and services purchased in Scotland from UK wide companies, will be recorded as paid in London as will taxes on the profits of any company HQed there. (This anomaly is one of the reasons why the City of London always appears in stats as the most profitable 'region' of the UK). The recently released GERS figures which show, according to the right-wing Unionist press and media, that Scotland's balance of payments deficit is second largest in Europe (only exceeded by Greece) are also affected by these same methods of recording income, revenue and tax generated by where the tax is paid (mainly London) rather than where it is generated (e.g. oil revenues). An outstanding example is that all revenues for Whisky (entirely produced in Scotland) are credited not to the Scottish economy but to the southern ports from which it is exported. Also included in the figures are the billions spent under defense budget expenditure for Trident - as if Scotland were responsible for the entire cost of the base and weapons (which we do not want) rather than sharing the the cost of this UK 'asset' proportionately across the whole country.
This does not affect only Scotland but also Wales, N.I. the SW and North of England giving a skewed picture of the profitability and tax take of each country and region.