A cuántos estamos hoy? - it is wrong. Sound like to ask for weather (degrees celsius). Cuál es la fecha de hoy? It is about the day(Januay 13th ) and Qué día es hoy? It is about the day (monday, saturday)

Hola: Soy de Colombia y no conocía la frase. Hoy, para mi sorpresa, encontré esto: http://lema.rae.es/dpd/?key=hora Hi! I am from Colombia and I had no idea this was possible. I found this today: http://lema.rae.es/dpd/?key=hora

A cuanto estamos hoy? < I don't know if this phrase is correct or not but it is very common, in english it means -At how many (days) are we today-So the answer is something like "Estamos a 15" -We are at 15th- In this question is already implied that you know the month and year. Cual es la fecha de hoy? =What date is today? this one is very clear Que dia es hoy?=What day is today? < this is asked to know the day of the week. Now in adition to the ones above A que estamos hoy? Is also very common and in this one you need to say the complete date .It means -At what (date) are we today?