While Gambit Gaming's former teammate "D4rker" will be assisting the team in Dreamhack, there's no mention of him staying with the team after Dreamhack ends.
After Edward has made the shocking move from Gambit Gaming over to North American team "Curse Gaming", The team has picked up "D4rker", a former teammate for the team back in their "Moscow 5" era. While he will be accompanying them for the first week of LCS at Dreamhack, there are no claims that he will stick with the team afterwords. Here's a quote directly from the statement after Edward departed from the team:
We've also received word from an unnamed source that he is not confirmed as a fifth, even though that is what is listed from LoleSports. The future of Gambit Gaming's roster as a full entity is still uncertain.
Source - Gambit Gaming