Press Association Sport understands the 22-year-old midfielder wants to hear what the Barclays Premier League outfit have to say after they tabled a bid of around £5million.
Johnson, who has scored 12 goals for the Coca-Cola Championship club this season, is out of contract at the end of the current campaign.
Strachan confirmed on Thursday that a series of potential buyers had contacted the Teessiders, some of them with verbal offers and at least one with a formal bid.
He said: "We have had verbal offers in the last week for Adam, but nothing has changed. Adam is still here and I would expect him still to be here for the last 19 games of the season.
"We have had verbal offers, we have had one official offer and I would imagine after looking at those that Adam will be here for the rest of the season, which we are quite delighted about because he is coming back into form."