SEN can qualify in a few ways.
SEN basically needs to win against LOUD going 4-2. G2 loses to LOUD going 3-3. NRG either beats EG (giving Alpha group 4 slots) or loses to both EG and 100T (going 3-3). In either case then, SEN qualifies. If NRG loses to EG and wins to 100T, then they are 4-2 and there is map/round diff tiebreaker.

BUT, if LOUD loses to SEN their playoff chances are done, so G2 has a much higher chance of beating LOUD. So things in Alpha are most likely coming down to map and round diff with a 4-2 tie between SEN, G2, and KRU (and possibly NRG) and two or three of these teams (if EG loses) . Impossible to predict what happens then.

Based on this, if SEN play well (2-0 both teams) I expect that their playoff chances to be relatively decent.