Today I decided to make an experiment. I asked my children a question on wich each of them had to said today (Сегодня). So my son (he is 17) ansverd Сёдня (syodnya), my doughter (she is 9) said Севодня (sevodnya).

Im am totally agreed with first opinion. it correctly sounds like ‘sevodnya’, but, and it’s important that writes as ‘сегодня’

"Sevodnya" is right. "Segodnya" will always be wrong I think, well maybe there are some cases in which it will be right, but it is very unlikely and I don't know them anyway.