The easiest is to have each company's revenue in a separate column but you could make it work either way. If you have a long table i.e. Company Names are held in different rows you can write a calculated field like
IF [Company Name]='X' then [Revenue] END
and another calculated field like
IF [Company Name]='Y' then [Revenue] END
To break them into separate columns using calculated fields in Tableau. This treats rows that don't have that particular company name as NULLs so when you SUM etc. they are ignored.